My 2 cents: in Marvell's time, the idea of "seizing the day" may have seemed more pressing than it does today, partly because lives then tended to me much shorter (and nastier and more brutish) than is generally the case today.  On the other hand, most people in Marvell's time and place took for granted the idea that there was an afterlife and that one might, in that afterlife, enjoy eternal happiness in heaven. (Let's not even discuss The Other Place.) Today, however, many people doubt (and are free to doubt) the existence of an afterlife. For those people, the idea of getting as much fulfillment (of whatever kind) out of the here and now, while there is still time, is very appealing.

(I would urge you, by the way, not to assume automatically that Marvell agrees with or endorses the arguments made by his speaker.  A strong case can be made that "To His Coy Mistress" is highly ironic.)

If you speak of "the carpe diem poem" as a genre, then it's long history going back to at least Horace indicates that it has not previously been nor is nor is expected to be outdated. History records variations on the seduction theme made infamous--oh, excuse me, that's famous--by Marvell. One such variation was offered by Baudelaire who gave the advice to live the life of your choosing--of virtue, of dissipation, or of dedication--as though intoxicated; this is his metaphor for living with enthusiasm and verve: ""Wine, poetry or virtue, as you wish. But be drunk."

The theme of the poem, at its core, is "act now because we may not have tomorrow." This philosophy is not new and it will never grow old because it reflects human nature, and the inherent nature of man doesn't change. It is a theme you can find in literature over the centuries, and we know that literature is a reflection and record of society.

What a great question! I agree with some other editors in suggesting that, whilst the theme of using carpe diem arguments to get a woman to sleep with you may be anachronistic, the overall theme of carpe diem is still just as painfully relevant today as it has always been. Certainly advances in health care and technology has meant that today's society has been able to ignore death a lot more successfully than previous societies, but that does not eradicate it completely, and the theme of our own mortality and ephemeral nature is still seen in a number of recent films, plays, books and poems. Carpe diem literature seems to be inextricably intertwined with the condition of being human, ensuring that it is here to stay.

I don't think the poem is outdated at all.  Even if, as pohnpei397 suggests, a woman's virginity isn't as valued as it was 300 years ago, there is still a double standard for women and men in the sexual realm.  Its great for the reputation for a man to have a lot of experience, but a girl is regarded as a slut.  Maybe it's a stereotype, but I still observe in popular culture that the boys are pushing harder for a sexual relationship when it comes to young dating.

Carpe diem poems in general are not outdated, but a poem that is about a man trying to wheedle a woman into sleeping with him is somewhat outdated.

Today, the idea that female virginity is a huge asset to be jealously guarded is seen as patriarchal and outdated.  Men may still try to con women into sleeping with them, but the main reason for women to resist is no longer the idea (as in Marvell's poem) that the need to stay virgin.  It is more that the target of the wheedling is reluctant to sleep with that particular man.

So, the idea of a carpe diem poem is not outdated, but the idea that is behind Marvell's poem (the idea of the value of female virginity and the need to protect it) is fairly outdated in today's world.

The essence of this poem is seduction, so if seduction is dated, the "To His Coy Mistress" is dated as is Shakespeare's Romeo and Juliet also dated, and so many other works.  For all, no matter in what era they live, time seems to flee, and joys must be grasped when they can.  Certainly, in this modern age, while the phrase "That long virginity" may not be as applicable as in Marvell's era, the concept of the sense of urgency is still relevant:

Now let us sport us while we may,

And now, like amorous birds of prey,

Rather at once our time devour

Than languish in his slow-chapt power.

Even in turbulent times, such as those of this twenty-first century, when people may long for the grave to end their woes, Marvell suggests that even the grave is too private a place to not have the joining of two warm bodies, to "there embrace."  Thus, it behooves all, no matter where or in what circumstance, to carpe diem.

I believe that "carpe diem" poetry, in general, is still very much a contemporary concern. If Andrew Marvel's generation saw life fleeting, certainly our contemporary society must see it moving so much more quickly, as life flies past on the wings of progress—for example, in medicine, technology (especially), and the number of things we try to fit into a single day. Children seem to grow up faster, in good and bad ways. Our little girls want to dress like movie stars and look older than they are. Our children in general want to leave childhood behind for the freedom they believe comes with being older, never seeing the worries and tribulations that come with aging (full-time jobs until retirement, worries over raising children, paying bills, keeping marriages working, trying to "fix" the world, etc.). And with a society that moves seemingly at light-speed, we also have the concerns of dangers to our young from this "new" society.

The sense of the "instantaneous" is stronger than ever with regard to fast food, instant messaging, the world at our fingertips with the Internet, etc. More and more people seem desperate to slow their days, and therefore their lives, down. I do not believe the topic is out-dated at all. In fact, should the people of Marvell's day actually be able to see the pace with which we live (by choice or necessity) our lives, they would be hard pressed to make sense of it—much the way we are!