In a move that reflects how news and events often break quickly or sometimes first on Twitter, the MLA has released the 'standard' format for citing tweets.
Its academic value is debatable, and although it probably will not take the place of a journal or full research publication in terms of academic value, a tweet can offer value in a number of other ways.
Sometimes, especially if received from volatile, politically unstable places, tweets can pack quite a punch out of a mere 160 characters. As a means of conducting academic research, Twitter can be a rich platform for both academics and businesses to explore public opinion on topics, gain news 'from the ground', and check for updates on a situation more quickly than traditional media outlets can publish.
More and more, Twitter can be considered a valuable resource for research and thesis creation. Due to this, the Modern Language Association (MLA) has released the 'correct' format that is suitable for citing tweets for academic purposes:
The tweet has to be cited both in the paper itself and the bibliography. After citing the author as above, the tweet has to be provided without changing any of the formatting, including capitalization. You also must conclude the tweet with the date and time -- using the time zone of the tweeter, not yourself -- and then use 'Tweet' as the means of publication at the end of the citation.
An example of a properly cited tweet is:
Osborne, Charlie (ZDNetCharlie). "How to cite a tweet in academia can be difficult." 6 March 2012, 3:53 p.m. Tweet.
For the main text of the paper, the tweet could be cited thus:
Charlie Osborne noted that "citing a tweet in academia can be difficult".
It seems quite odd that as a resource found online no web address is required -- especially considering the future difficulties of validating such a source after a few days. The only way to access past tweets is to use one of Twitter's partners Datasift, who for the bargain price of $1000 per month allows a user access to the millions of tweets posted previously.
However, just because there is now an official, standard format does not mean that you should necessarily reference tweets. It is always worth checking with your professor to see if your university allows it, and if so, you should not cite tweets just 'because you can' -- or because you want to see how many times you can get away with writing 'Tweet' in an essay.