A newly-announced service from Twitter, called @anywhere, will eventually allow people to add the Twitter experience to any website:

Imagine being able to follow a New York Times journalist directly from her byline, tweet about a video without leaving YouTube, and discover new Twitter accounts while visiting the Yahoo! home page—and that’s just the beginning.

The service will debut on several major web destinations, including Amazon, AdAge, Bing, Citysearch, Digg, eBay, The Huffington Post, Meebo, MSNBC.com, The New York Times, Salesforce.com, Yahoo!, and YouTube.