Xbox Live users who only have the original PS Universe have received a great present from Sega! According to a recent Sega America blog post, the Ambition of the Illuminus expansion has been made available for free over Xbox Live.
So if you've got the original for Xbox and have been holding out on getting the expansion, this seems like a good time to make the leap. There's also a new game update, called "GUARDIANS Advanced Content update" with improved features available now.