Thanks for this handy piece of software. It's the only free program I found which does tags and versioning, two essential features of a photo indexer. I would love to be able to help out but unfortunatly I know nothing about C# so I'll just have to request features instead. 
Would it be possible to impliment manual versioning? The way I see it is that you select a number of images then click a 'create version set' button. Then you choose which is the primary image and viola! This would be useful if there are any images already edited before importing them, and also for panoramas. The big picture would be the primary image and all the other images used to make it would be children.
On a purely asthetic note it might be nice to split the photo's into year, month or day sections in the main view, with a heading for each separate section.