[motters]

Since notifications from Facebook will contain mostly predictable content won't these just become cribs for crackers?

[dionyziz]

Not sure what you mean, but good encryption algorithms (including GPG's RSA and DSA) are not vulnerable to known-plaintext attacks. Even if you know the plaintext and the cryptotext shouldn't help you in cracking the key in any way.

[__z]

I dont facebook very often so every few days they send me a notification email "myname you have notifications pending." even when i dont.

[lmm]

Modern crypto algorithms are considered broken if they're not secure against known-plaintext and even chosen-plaintext attacks.