I rarely log on to deviantART - but whenever I do, I find a bunch of messages with questions about usage of my custom shapes. So here's the deal:
Use them for whatever you like, just don't SELL THEM. You can sell t-shirts, posters, website designs or whatever where my shapes are PART of the art that you've made, but please don't sell the "clean" shapes.
That's it, really =)
(Oh, but I DO enjoy looking at what you've made from them, so keep posting those links!)