###Update - the 32-bit version is also available now.###
Released this morning. Details are
Download from http://www.oracle.com/technology/software/products/database/index.html
And according to http://download.oracle.com/docs/cd/E11882_01/install.112/e10843/toc.htm
* Windows Server 2003 - all editions
* Windows Server 2003 R2 - all editions
* Windows XP Professional
* Windows Vista - Business, Enterprise, and Ultimate editions
* Windows Server 2008 - Standard, Enterprise, Datacenter, Web, and Foundation editions. The Server Core option is not supported.
* Windows 7 - Professional, Enterprise, and Ultimate editions
Note: Check My Oracle Support (formerly OracleMetaLink) for more information about Hyper-V support.
No discussion in doc or in Support about 2008R2, even though it is a different core to 2008 (same difference as Vista to Windows7).
The release information discusses both32 and 64 bit. Keep checking for the 32 bit download if you need that.
Install guide is at http://www.oracle.com/pls/db112/portal.portal_db?selected=11&frame=#microsoft_windows_installation_guides
The database software is in 2 zip files, which include the database and companion distribution. Unzip them both into the same directory.
When you get the software, MAKE SURE you get the deinstall download as well. It is the only correct way to remove the software, and (on the *nix platforms) it does an excellent job.
ASM is moved to the Clusterware, so if you want ASM you will need to get the Clusterware s/w and install that first.