JDeveloper will notice that there are two "current" releases to download, 11g Release 1 and 11g Release 2 (abbreviated to 11gR1 and 11gR2 respectively). 11gR1 encompasses the 11.1.1.X.0 JDeveloper versions including the latest 126.96.36.199.0 release. 11gR2 encompasses the 11.1.2.X JDeveloper versions including the latest 188.8.131.52.0 release.
What's the difference between the two releases and when would you want to use them?
JDeveloper 11g Release 2 includes support for JavaServer Faces 2.0 and was released for customers who are specifically interested in using this contemporary Java EE technology. Oracle plans to bring in full Java EE 6 support in JDeveloper 12c which JSF2.0 is apart of, but in listening to customers there was interest in obtaining the JSF2.0 support earlier. Thus the 11gR2 release.
The question begs then why would you want 11gR1 if 11gR2 includes the latest Java EE JSF standards? Surely 11gR1 only supports the older JSF1.2? The answer revolves around JDeveloper's Fusion Middleware (FMW) support. Only 11gR1 and the yet-to-be-released 12c versions of JDeveloper will support the full FMW tools including WebCenter, SOA Suite and so on.
So if you want the latest JSF2.0 support go 11gR2, but if you're happy with 11gR1 or need the rest of the FMW stack stay on the 11gR1 platform for now as Oracle is continuing to actively improve it. Eventually JDeveloper 12c will arrive where the 11gR1 and 11gR2 releases will converge, and your choice will again be a simple one.