In case you intend to run el6 on an older hardware, you are not alone; you can avoid the labor of rebuilding the kernel on your own using the one I did. Get it here: http://repos.fedorapeople.org/repos/lkundrak/kernel-nonpae/
Most likely you're probably not going to use it with a paid RHEL subscription, since it will post likely not be supported anyway. You can get mostly complete rebuild from Scientific Linux at this point; or choose to wait for CentOS (which is likely to provide a non-PAE kernel as well once updated, rendering this obsolete).
I've updated the kickstart for the live media for Scientific Linux repository, if you intend to try it out without installing: http://v3.sk/~lkundrak/blog/entries/rhel6-live.html
NB: Note that the repostory lacks debug kernels and debuginfo since I would run out of disk quota. Just let me know if you need those.
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Mail questions, comments and pizza to lkundrak@v3.sk