I'm not really out in front of this one, but I'll do the obligatory post.
11g was announced back in early July in the UK, followed shortly by an announcement here in the States. Every since then, I'll go to OTN, downloads, OBIEE to see if was generally available. I've done this every day for the past month. On Friday, I did the same thing and 10.1.3.4 was still there. I then got an email from my boss that evening saying it had been released. I guess I can't first for everything.
To download the latest and greatest, go here. The Overview is here. And finally the documentation.
I downloaded it on Friday evening (nerd) but haven't installed it just yet. I'm hoping to get to it this week. I wouldn't say I'm excited...I'm still in my learning phase...so it just means a bit more work. I'm sure it will be fun though.
Mr. Rittman, I believe, has written a book on 11g, which means he's had it for quite some time. Get on over there to see a host of articles pertaining to the new release. I'll start with the New Features section, the install, and probably head on over there.