Skype has updated its iPhone app to version 5.2, which brings voice messaging back. Incoming messages now show up among your conversations and can be reviewed at will. Just tap to listen.
Also, version 5.2 lets you review a contact's information with a tap, including their name, birthday, location and "mood message." There are other changes which you can review here, but the big news of course is voice messaging. Download it now and get Skyping.