Why not? They have enough mathematicians and cryptographers on payroll that they can analyse the major protocols and software that is used. If you look at the recent attacks on TLS - especially the downgrade attacks to export grade ciphers they would be stupid to not exploit this for targeted attacks.
That being said I doubt they'll have very good mathematical attacks as a lot of researchers look at this stuff but implementation bugs, side channel attacks and plain bugs are plenty.
most of the world runs openssl or CryptoAPI - why not spend a few man years looking through these implementations?
Well at least if I where them I'd have some programmers to come up with automatic bug finding techniques and fuzz the hell out of existing applications.
They also likely don't care about your encrypted facebook chat but government infrastructure, mobile telecommunication providers and lots of important enterprises are probably pretty often on their "we need to get in list" if you can decrypt captured encrypted traffic - I imagine this would be a huge net win.