This is breaking news at the moment, therefore this post will update as new information trickles in.
Similar to the way that it rolled out Lists, Twitter is incrementally releasing its new Retweet feature initially previewed in August 2009.
As described by @Biz, co-founder of Twitter:
Retweet is a button that makes forwarding a particularly interesting tweet to all your followers very easy. In turn, we hope interesting, newsworthy, or even just plain funny information will spread quickly through the network making its way efficiently to the people who want or need to know.
The plan is to see how it goes first with this small release. If it needs more work, then we’ll know right away. If things look good, we’ll proceed with releasing the feature in stages eventually arriving at 100%.
The new retweet feature is particularly interesting as it organizes your experience directly at Twitter.com much in the same way third-party clients such as Tweetdeck and Seesmic have offered all along. Unlike these desktop applications however, Twitter.com remains as the pervasive interface for engaging on Twitter. For example, your lists, real-time search results, DMs, Twitter stream, and now retweets are key pillars to the personal experience at Twitter.com. For most users, the new retweet functionality, combined with important, cached searches (including your username), the need to stray from Twitter’s online hub begins to dissipate. And, the timing couldn’t be better…
Here’s a screenshot published on Mashable (Thank you Tonya Becker-Haddadeen):