Skype have just released Skype 5.6 for Mac, and includes a few new features and improvements, such as:
Improved UI for group video calling
New full screen mode in OS X Lion
Ability to delete conversations
Ability to disable Audio Gain Control
Skype now pushes through automatic updates, so when new versions or minor (and critical) updates are released, Skype will continue to keep you up-to-date. Group video calling gets its user interface lifted, where there's now dynamic and non-dynamic mode in group video calls with 5 or more users. With dynamic mode on, the person who is speaking is automatically moved to the top of the screen.
Full-screen mode is now supported by Skype for Mac in OS X Lion, where it eliminates the Dock and Menu bars totally. Included is also the ability to delete messages within a conversation, as well as remove conversations from the sidebar, and history.
You can download Skype 5.6 for Mac, here.