Fedora 15 with stock kernel on Rackspace Cloud

I recently found myself needing a more bleeding-edge cloud server than the Fedora 14 servers I have been running on Rackspace Cloud. Rackspace is not yet offering a Fedora 15 image for new servers, so I needed to start with a Fedora 14 system and upgrade it. I also needed the kernel to be more current than the kernel Rackspace currently uses with Fedora images, and I am not sure the upgraded userspace would work with that kernel and init image pair anyway.