I would hazard a guess that they will force you onto this...
Pricing Schemes
http://www.janrain.com/products/engage/pricing
Also you can see a demo on a wordpress site i found...
http://foreclosurefraudnews.com/
I'd like to know
- Does it play nicely with the intergrated facebook connect?
- what happens to existing accounts, if I uninstall the mod?
- Is the 2,500 limit new registrations per year or a hard limit?