[mcmc]

I prefer Costco to Best buy any day. What matters far more is reputation and the quality of the product than the barrier to entry to join/utilize the product.

Facebook could add a ten page signup form and I doubt it'd substantially impact their legitimate signup rate.

[ambirex]

I suspect that Lazy Registration/Progressive Signup is far more important for lesser known sites. Facebook has the weight of some 500+ million users behind it and there is sufficient motivation for new users.

When working on wedding proofing sites I found that users would be willing to put up with more steps because they were motivated to begin with.