WPKGExpress adds a web frontend to WPKG - it does work - I found the setup was surprisingly straightforward, if a little daunting due to the lack of documentation..
I have bought Prism Deploy Packager (which is the packaing technology part of the prism deployment suite) - this is remarkable value, if bought on its own, and creates nice install packages that never ask for elevation on Windows 7 and most packages, though created on XP, still work on Win 7 - WPKG has no problem deploying these. WPKG/WPKGExpress is a bit of a monster to manage the groups, packages etc. if you have a lot of kit, and doesn't provide a lot of feedback on success of installations..
I am currently trialling Specops Deploy - which could be described as the Windows Equiv. of WPKGExpress. Due to the nice integration with AD it will certainly save time and effort, provides feedback on success, failures etc.. It adds the ability to deploy .exe files (inc. those generated by Prism Packager) to GPOs - and much more.. (including a wrapper to simplify MDT for OS deployment - still playing with that!)
John