They say they already have Amazon, AdAge, Bing, Citysearch, Digg, eBay, The Huffington Post, Meebo, MSNBC.com, The New York Times, Salesforce.com, Yahoo!, and YouTube on board, which is an amazing start. (And notice Google is notoriously absent from this list...) And considering this is supposed to be Twitter's answer to Facebook Connect, they are doing a pretty damn good job. The integration aspect of the service is certainly beyond the common usage of Facebook Connect, which for me has only logged me into sites and allowed websites to post to my Facebook. Twitter's @anywhere seems like it plans to really become a part of the website, rather than just be a connected third-party script, which will definitely help them in the long run.
For now, @anywhere is just a placeholder, but the upcoming weeks and months of Twitter integration might bring a change entirely how we think and use Twitter as a service.