So what's new in this release:
1) Enhancements to Real Application Cluster, Oracle RAC One Node option is now available for relatively less critical systems. The ASM get's a face lift with intelligent data placement leading to better retrieval rate for data.
2) Advanced data partitioning to allow more online application upgrades.
3) One of the Exadata related feature is called “Warehouse” Compression and is based upon Exadata Hybrid Columnar Compression. This technique delivers a typical compression ratio of up to 10:1 for data warehouses, with virtually no negative impact on query performance, per Oracle. The "archive" compression can get 40:1 compression factor.
The 11gR2 documentation is here.