I'd recommend to encrypt the swap (maybe with a passphrase instead of a random one time password, I don't trust the entropy pool while booting up). No swap at all might get nasty if you hit your ram constraints.
Well the most sensitive keys will be kept on an offline computer which presumably runs nothing else except offline Armory. There's not really a way to run through your RAM there. Plus, I'd rather run out of swap than have the keys accidentally hit the hard drive unencrypted without warning. But yes, it is possible to have encrypted swap, though I don't think you can use hibernate if you do that, so you'd be disabling hibernate which is 80% the reason you wanted encrypted swap to begin with.
Encrypt the whole OS with Truecrypt and you dont have to bother anymore... though TC is somewhat in a strange state... now that the devs dont want to work on it anymore.
As far as I know, TrueCrypt doesn't do encrypted swap. It makes sure that nothing touches your
primary (storage) partitions unencrypted, but if you hibernate with key material in RAM, it will still end up on disk unencrypted. I recommend both disabling swap (and hibernate), and use full-disk encryption. TrueCrypt works for the disk encryption part, though most recent versions of Ubuntu have had home-partition encryption in the OS-install wizard for a while
If TC encrypted an OS then everything is encrypted, including the swap-file. You only can get back into the hibernated session if you insert the password first since the swapfile is only a file on the OS-Partition. And the whole OS-Partition is encrypted.