• Web page addresses and e-mail addresses turn into links automatically.
• Allowed HTML tags: <a> <em> <strong> <cite> <code> <ul> <ol> <li> <dl> <dt> <dd>
• Lines and paragraphs break automatically.

• Links to specified hosts will have a rel="nofollow" added to them.

• Twitter-style @usersnames are linked to their Twitter account pages.
• Twitter-style #hashtags are linked to search.twitter.com.

More information about formatting options