PGP Interoperability?

Can anyone out there vouch for the interoperability of PGP 2.6 ui with versions of PGP available in USA from MIT & Viacrypt. What about the legal issue ? Is it legal for a US citizen to encrypt or check signatures with a 2.6ui public key ? Would sending a public key out of the US be reagarded as export by ITAR? Thanks Geoff Klein.