We've talked about a few different Twitter clients designed specifically for Honeycomb in the past, but none have been so anticipated as Tweetcaster HD. The standard Tweetcaster (for phones) has been a long time favorite app of Twitter users because of it's super-rad zip it feature, which gives you the ability to block tweets by keyword, so you can ignore annoying tweets without having to un-follow anyone. Now, along with several other nice features, you can have this functionality on your Honeycomb tablet!
Aside from Zip It, you can also color code tweets, retweet with or without comments, view @replies in a conversation style breakdown, and much more. It also supports Facebook integration, as well as support for multiple Twitter clients.
You can grab Tweetcaster HD for free in the Android Market.