Easiest way to compare pkg versions?

[John Klos <john%ziaspace.com@localhost>]

Given a pkgsrc directory for a package (say, shells/tcsh) and a binary 
package (tcsh-6.20.00nb2.tgz, for example), what's the easiest way to 
determine whether the binary package is up to date compared with the 
pkgsrc directory?

Thanks,
John