Gigya seems like a very nice solution for social network login/signup. You can connect existing accounts (on WP) (this to me is the killer app — users having their BP account connected to their other social network accounts), users can signup with various services once you have the APIs configured on their site, you can use the widget to let users invite friends from their other networks.
Very nicely-thought-out, rich developer doco on the Wiki, and a pre-existing standard WordPress plugin (and I’ve found some hints via Googling that it works with MU as well).
I fired them off a support email yesterday to ask if they were willing to look at BP integration on their end a bit, but haven’t heard back.
Given that the FBConnect plugin here doesn’t really do the job, and this offers a lot more (FB, Yahoo, Twitter, Myspace, etc) I wonder if anyone else is looking at this (I’ve got everything connected up in the background, but am chasing configuration issues), and if so, if you want to share notes.
Have a look if you haven’t, let us know what you think. And if you’ve got it working with BP, please share how you did it?