While it's nice that Pidgin-Encryption can generate its own keys, I'd much rather prefer to use existing X.509 certificates that I have.
For example, I have certificates from Thawte, CAcert, Comodo, and other public CAs. It'd be nice to have Pidgin-Encryption be able to access the Mozilla (or Windows, if one is using Windows -- I'm not) key store and be able to use the users existing certs.
This might prove helpful for interacting with standard AIM, as they use such certificates and provide some useful information in the IM window such as "This message is encrypted." and "This message is digitally signed by [name on certificate]."