You can now try out the next version of DB2.
I've talked about DB2 Viper, the next release of DB2, which will handle both relational and XML data. IBM now has a DB2 Viper Early Community page, which lets you download a beta and try it out. There's also a new article, "What's new in DB2 Viper."
Update: As Andy Piper notes, C. M. Saracco has two articles on DB2 Viper:
DB2 Viper Test Drive