Skype for Windows Phone has been updated to version 2.25, bringing a number of enhancements and fixes. Chat is a particular focus of this update.
Users can now choose what to delete in their messages, either getting rid of a single message or clearing a whole conversation. Any messages you clear will still show up in Skype on other platforms. For group chats, you can now see all avatars in a group, and they'll update in the app, as well. You can also add groups to your favorites list. Also, if you send a message with only an emoticon, it appears nice and big on the chat screen.
You can download Skype 2.25 from the Windows Phone Store right now.