Oracle XE 11gR2 beta has just been released, some details here and download here. It’s not a great deal of use for sandboxing DWH-specific stuff, given this list of excluded functionality (and this is by no means everything that’s not included):

• Bitmapped index, bitmapped join index, and bitmap plan conversions
• Oracle Partitioning
• Parallel Data Pump Export/Import
• Parallel query/DML
• Parallel Statement Queuing

(source)

However, it’s always interesting to have to hand for trying out other things. And I like playing with new toys :)