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Twitter has announced their new Follow Button. The follow button will allow users logged into Twitter to follow you directly on third-party sites by clicking the button, for users not logged in, you will be taken to the Twitter profile.
Here is my follow button (feel free to follow, if you don't):
Here is the Search Engine Roundtable follow button:
As you can see, you can customize the follow button.
You can create your own over at Twitter's resources and for even more customization methods see the developer documentation.
This announcement came the day before Google is expected to launch the Google +1 button for publishers.
Forum discussion at WebmasterWorld.
