Acrobat PGP Plug-in is coming along nicely.  Basic functionalities are working.  UI is still mostly just PGP's boring built-in stuff.  I want to put up a custom UI so I can handle other signing methods as well as different versions and variations of PGP like GnuPG.  Currently, only PGP 8 is supported.  I am not planning to do an OS X version until later.  If you have any requests, this is the time to do it.  Detached signature and XML-DSIG features will not be there until after the first version is released.  I love fun little projects like this.  Designing large systems is fun too, but there is nothing like designing personal products that people will use everyday.