[michael_dorfman]

I don't disagree. The question in both of the cases you mention comes down to value-- in both cases, the marginal value provided to the user is too small. The fact that people are using your site doesn't necessarily mean that there is much value there to be extracted.

I'm not suggesting a "monetize-later" strategy, mind you, but if that's the plan, I'd think it a good idea to make sure you have something that can actually be monetized.

[logicalmind]

Another thing that is somewhat interesting about the social networking aspect of some of these ventures is that it makes it easier for people to socialize against you. This could mean something like "fight facebook so they don't charge us" to "let's move to shmacebook they have cool feature xyz". So switching from non-pay to pay could be more troublesome than anticipated.