Those 500 million Facebook users sure seem tempting.

It appears as though the number of payments providers through Facebook are growing exponentially. Beyond Visa’s Playspan and PayPal, there are dozens, if not hundreds, of options. Add SociallyPay to the list. The service, which went live on Facebook on Feb. 25, offers “single button” payments. SociallyPay also works through Twitter.

SociallyPay is based in Euthal, Switzerland, and is headed by Falk Wolsky, who runs a firm called BeautifulBinaries.

But I’d argue that SociallyPay, and the other payments efforts on Facebook, are secondary to Facebook’s payments platform, Facebook Credits. Just last week, Facebook took some major steps to firm up the role of Facebook Credits on the site. I’ll address the changes in a separate blog, but suffice it to say, they do not bode well for SociallyPay, et al.