To add a bit more detail to Ben's mail, OpenPGP:SDK is a new open source library, available under a Apache-style license. It's a completely new implementation of the OpenPGP spec, and is available at <http://openpgp.nominet.org.uk>.
At EuroOSCon, we discussed a number of applications which could be developed using such a library - using PGP keys inside the X509 certificate for web authentication was one such application we used as an example. If you're interested in writing such an application, please take a look at OpenPGP:SDK. We might well write a demo of this ourselves, but it's a question of priorities at the moment, so no guarantees about when... Rachel
