The new methods of communication do not differ significantly in content or in “speech-acts.” We are still basically saying “hello,” “keeping in touch,” “passing information,” etc. The primary overriding difference is succinctness, abbreviating language on the assumption that the receiver can “fill in” what is abbreviated. The basic communication model – sender, code, medium, static, receiver, etc. – is still intact, but now the “exchanges” – the pairings of utterance A, response to A, etc. – are quicker and more conversational than letters, quieter than oral conversation, less “wordy” -- that is, “modified” with adjectives and adverbs, etc. – and interestingly, more private than 20th century conversation (cf. phone conversation to Twitter).
Another interesting social change is the extensive range of people who can join in on the conversation – thousands of Tweeters, for example. Finally, our modern social structure is being altered by the presence of electronic communication – in myriad ways – bringing us together abstractly while separating us physically. I see a parallel in the Interstate System, sold to us as a way of connecting us to each other, but in fact acting as an excuse for the nuclear family to spread out across the country. From a linguistic standpoint, the sentence conventions (subject, predicate, object) are still there but much of the structure is implied rather than overtly stated: OMG still “means” Oh, I am amazed by your last utterance.”