Source RPMs (.srpm) are being uploaded to http://oss.oracle.com/ol6/SRPMS-updates.
OL6.3 contains UEK2 kernel-uek-2.6.39-200.24.1. The source rpm is in the above location but our public GIT repository will be synced up shortly as well at https://oss.oracle.com/git/?p=linux-uek-2.6.39.git;a=summary. Unlike some others, of course, complete source, complete changelog, complete checkin history, both mainline and our own available. No need to go assemble things from a website manually.
Another cool thing coming up is a boot iso for OL6.3 that boots up uek (2.6.39-200.24.1) as install kernel and uses btrfs as the default filesystem for installation. So latest and greatest direct access to btrfs, a modern well-tested, current kernel, freely available. Enjoy.