A better approach, I think, is to ask how to build a first rate church system with EE and to equip it with a means to push out to tools like Facebook and Twitter automatically, seeing them as new distribution channels of information.
I’m already using tools like Ping.fm and HelloTxt.com to push Twitter-sized updates to multiple networks. One entry goes to (in my case) 6 other networks (there are dozens, and some with varying media types like Flickr). These web apps really have this integration figured out: it would be interesting to learn from their approach. Lots of API hooks into each network. I’m still trying to figure out how to ideally leverage it into an EE site (via MetaweblogAPI perhaps).
The other direction - pulling in content, identities and the like from these other networks - is less developed. I’m still on the sidelines, watching.
This is an incredibly pertinent question heading into 2009. Can EE be both a social-network aggregator and “social network CMS”?