Cut out the middle man. Hey mom, I encrypted this bitcoin private key with your PGP. Decrypt it and use the import key utility built into bitcoin v1.2.04.
I like this. Richard Rahl, it doesn't have to be any harder than "after you download and install Bitcoin, open the attached Bitcoins" (Content-Type: application/bitcoin-privkey-transfer [hypothetical]).
Encryption with PGP is complementary and composes nicely into the whole MIME hierarchy. Forget about PGP for $10 worth of Bitcoins to Mom, but for a $10000 transfer, you bet.
Some discussion on key export formats: