For those of you who regularly VPN into work and are planning on purchasing an Apple AirPort Extreme 802.11n, check this out. According to the Apple Support forms, VPN users have been having trouble with VPN pass through because there aren't any options to configure the pass through.
There is a workaround, however, to use in the meantime while Apple releases a patch. The workaround has you setting the default host and pointing that to your machine you need to VPN from, but it's less than idea if you need to get more than one computer to VPN. Take a look at the support forums for more info.