Facebook seems to be much less recession-resistant than Google.
Facebook, which sells ads to marketers hoping to create demand, rather than fullfill that demand the way Google search ads do, may be much more vulnerable.
Google actually fared OK during the most recent US downturn. It fared well throughout 2008 and 2009 and only truly suffering a little in Q1 and Q2 2010.
If the US economy slows more than it already has – down from 2% growth earlier this year to 1.5% today – Facebook could face a painful shortage in demand from big brand marketers. That's the last thing Facebook needs as it desperately tries to reacclerate flagging growth with new ad products.