Beyond the simile mentioned above ("Now the trumpet summons us again—not as a call to bear arms, though arms we need—not as a call to battle"), Kennedy's inaugural address does not use any similes. Similes are comparisons that use the words "like" or "as." Similes are similar to metaphors: metaphors describe one thing in terms of another without using "like" or "as." Both similes and metaphors are the language of poetry and the imagination, and while Kennedy primarily uses declarative language, he also employs a few metaphors such as "the torch has been passed," which means not literally that people are handing torches to each other but that a younger generation is taking over power in the nation. He also uses a metaphor in the following: "those who foolishly sought power by riding the back of the tiger ended up inside." Again, he is not literally talking about people who rode on a tiger getting eaten by the tiger: he is referring to groups or people who backed dictators to in order to gain power but ended up defeated. These metaphors are somewhat cliched; however, they do, nevertheless, add variety to the speech.

A simile is a literary device that makes a comparison using "like" or "as."  In John F. Kennedy's inaugural address, the following is an extended simile:  

“not as a call to bear arms, though arms we need -- not as a call to battle, though embattled we are”

This section of the address calls Americans to seek out ways to serve the greater good, rather than look for their own success.  A few lines later, President Kennedy uttered the famous words “ask not what your country can do for you; ask what you can do for your country.”

A simile is a figure of speech in which two unlike things are compared using the words "like" and "as."  President Kennedy's Inaugural Address is full of descriptive language, very eloquent, and to the point.  I searched the whole piece and found two different passages containing similes (with references to the specific paragraphs they are in): 

" . . . we observe today not a victory of party, but a celebration of freedom --symbolizing an end, as well as a beginning--signifying renewal, as well as change . . . " Paragraph 1 

" . . . Now the trumpet summons us again--not as a call to bear arms, though arms we need--not as a call to battle, though embattled we are--" Paragraph 22

The entire speech can be found on many different websites, as well as in assorted reference books around the country.  Audio recordings have also been produced and archived for history's benefit.