I haven't even heard of that. On the one hand, it seems like a totally cool idea!
OTOH, it seems too hackable for my comfort. I'm sure some people will think up great phrases, but there will be phrases that lots of people gravitate to. Like, "I love NY." or "I love Edward" or something.
I think I'll wait and see how it works out before I join in.
Regarding PayPal, amma, I have an account that I haven't been able to use for much of anything. Almost no online places I know of even accept it. I'm not an eBay shopper.