This is going to be a super volatile stock. If the Q1 2012 revenue is flat QoQ, this is probably a $50B company, if it is up 15%, then this is probably a $100B company.
I agree that ads revenue growth will be key for them in the short term. The Q4 2011 vs 2010 growth was 44% and it seems like perhaps the growth rate is slowing down.
Of course they're not yet showing ads on mobile..
I think on balance mobile is not really an opportunity. They are losing the game revenue to the mobile/tablet platforms and in-app mobile monetization is a minimal opportunity for a task based application.
I don't use facebook, but can you explain what it means to be working on payments? I thought that was just their taking a 30% cut on game payments on their platform. That kind of margin doesn't exist for more general "payments".
Even with all my negativity, I am still cautiously bullish on Facebook. They are only making 50 cents/month per active user. I see no reason they can't double that.