The Mac has its fair share of Twitter clients, but only a few really stand out. One of the more recent ones is Kiwi, which was just updated to v1.2. Kiwi is developed by YourHead Software who also make some incredibly useful plugins for the RapidWeaver app.
I tend to rotate between a few Twitter clients, and Kiwi is one of them which has gained its spot in my rotation. One reason is it has a clean, usable interface. Second, it is theme-able, and there are some really slick themes available for download.
Version 1.2 has been updated with xAuth, new “retweet” support, username/real name choices, and inline image previews.
Kiwi has a limited feature free version, and you can register the full version for just $9.95 to unlock all the features available.