Tweet Button

Adds the Twitter buttons to your nodes.

Choose which content type, and if the button should show on teasers or full nodes.

More information:
http://blog.twitter.com/2010/08/pushing-our-tweet-button.html
http://twitter.com/goodies/tweetbutton

Branch 7.x-2.x

Features:
1) Tweetbutton will be a field. Can be attached to any entity
2) Each entity page can specify an author twitter account info, and a custom tweet text to be use as the text for the tweetbutton on that page.
3) The tweet text and author account can be token strings. One can create a user field "Twitter account" and add a token [node:author:field_twitter_account]. If no twitter account was specified, it will fallback to default site twitter account.