https://admin.fedoraproject.org/updates/fedora-productimg-cloud-21-5.fc21
See testing notes on desktop list - same basically applies. Can also test using product.img as an updates.img.
https://lists.fedoraproject.org/pipermail/desktop/2014-November/011178.html https://fedoraproject.org/wiki/Anaconda/Updates
The installer still isn't fully "cloudified" and really only makes sense for cloud images when used with our kickstarts from https://git.fedorahosted.org/cgit/spin-kickstarts.git/tree/. But, hey, might as well make it pretty.
Whoops forgot to change the subject. YOu can test both, of course. :)