Mashable posts that Mashable’s Twitter Guide Book Now Available for Download. It’s sponsored by Adobe so the guide book requires Acrobat 9 or Adobe Reader 9 for viewing.
You can read it online at Twitter Guide Book – How To, Tips and Instructions by Mashable which is described as:
a one-stop shop for getting up to speed with everything Twitter, from managing your Twitter stream to promoting a business. We’ve also included the latest Twitter lists and news from Mashable, plus community reviews of Twitter and related services from our sister site, Blippr. The Twitter Guide Book will be cultivated, maintained and updated to bring the latest tips and tricks as Twitter evolves.