File this under "it's about time" and "ICYMI (In Case You Missed It), but Oracle has released Database 12c (188.8.131.52.0). Downloads can be found on their TechNet and E-Delivery sites. At this point, the only available versions are for Linux (x86-64), Solaris (Sparc64), and Solaris (x86-64). Other platforms will surely follow.
Not officially released... yet
According to media reports (and my inability to find an actual press release from Oracle), the formal launch of Database 12c will occur "within a couple of weeks".
Differences between TechNet and E-Delivery
While, otsensibly, it may be the same software, there is always the possibility that you'll get slightly different versions. The software that you download from TechNet is usually in the form of either a zip file or a "tarball" of the staged installation. The downloads from E-Delivery are also zip files, but they represent the actual media packs (CD or DVD). For some reason, Oracle doesn't do ISOs, but, nevertheless, the E-Delivery downloads are typically viewed as more "supported". As a result, I recommend using the E-Delivery downloads rather than TechNet if you're planning on doing anything that is going to need to be handled under a support contract.
Naturally, for either method, you will have to agree to license terms and export conditions. If you have never used E-Delivery from your Oracle account, there might be a slight delay as your account is verified by Oracle.
As with all new software, be sure to test thoroughly and make sure any applications are certified with 12c before deploying to production.
Oracle Client 12c is also available
The Oracle 12c Client can also be downloaded for the following platforms: Linux (x86-32), Linux (x86-64), Microsoft Windows (x86-32), Microsoft Windows (x86-64), Solaris (Sparc 64), Solaris (Sparc 32), Solaris (x86-32), Solaris (x86-64).
NOT CERTIFIED WITH E-BUSINESS SUITE
Since this blog is focused on E-Business Suite (and E-Business Suite is what I do), I feel the need to state that Database 12c is NOT certified with ANY RELEASE of E-Business Suite at this point. I suspect that we'll see it certified against 12.1.3 and the upcoming 12.2 at some point in the future (maybe 12.2 on release). It is highly unlikely (in my opinion) to be certified against any release 11i. In the event that it is certified against 11i, you can bet that it will be a pretty low priority item.
You can find them available here:
Oracle E-Delivery: https://edelivery.oracle.com
Oracle TechNet: http://www.oracle.com/technetwork/indexes/downloads/index.html