Tweetbot is defiantly one of the biggest Mac and iOS Twitter Clients out their, and with there newest Alpha version it seems that Tapbots are making the software even better on the Mac, the update includes a lot of major improvements including keyboard shortcuts, support for notification Center and the usual performance improvements and bug fixes, check out the full list here:

• Notifications for mentions, follows, retweets, favorites (10.8 only)
• Go to User (command-u)
• Option to open links in background (see preferences)
• Less intrusive tweet action overlay icons
• Double-click tweets in timeline now takes you to status detail
• Fixed some contextual menu issues in direct message conversations
• Fixed pull-to-refresh and scrolling to top issue when loading new results
• Tweetmarker will now set your timeline position on app startup always
• Fixed bugs and crashers related to composing tweets.
• Made large and huge fonts bigger
• Can swipe the empty space in a conversation to go back to previous view
• Can close image window with command-w (also space and esc)
• Menu shortcuts added to profile view: Command-d (direct message) and command-r (reply)

The newest update is available now, just check for update son the current build, or head over to Tweetbot’s official website.