WordPress.org

How is this different then Twitpress?

1. Twitpress tweets all posts. In TwitCategory you can choose "All Posts" or a single category from which to tweet. Posts that are not in the specified category won't result in a tweet.
2. I changed the [permalink] variable to actually show that permalink as defined in your administrator settings (it used to show guid).
3. There are also a few new variables that you can use to modify your tweet: [guid] which shows the shorter guid link. [category] which displays the selected category. [post] which adds the post content to the remaining space.

I installed twitcategory and clicked activate, but my blog entries aren't being twittered!

Unfortunately twitcategory is not psychic. You need to configure your twitter username and password from the TwitCategory menu in the wordpress 'manage' menu

What is that extra junk for bitly?

Bitly requires a user name and API key. Go to http://bit.ly/account/register to set up an account. Your key can be found under 'account'.