Wow, that looks a lot (lot lot) like my current project, AppRabbit.com. Even the layout looks similar, although this is the first time I've seen your demo or heard about you guys, I swear! I love your approach, and your presentation and UX looks sweet! It's awesome to see other people dabbling in the same area I'm working in.
Ha we deadpooled in december 2008. This was a demo video from back then, but I did ressureect the code on my localhost last night for fun. Shoot me an email: j@jasonlbaptiste.com
A big barrier to something like your product is the notion of something replacing Excel spreadsheets. People love their Excel spreadsheets. They are used because there are a lot of perceived benefits. Such barriers could be avoided by solving the same problems as an adjunct to spreadsheets. (This makes sure that there's a backup of all your company's spreadsheets. You can roll back to any prior version. It also enables easier sharing of data...)
ObjectStudio Smalltalk could do interesting things with Excel spreadsheets through OLE. You could open a spreadsheet and pull data out of individual cells, etc... I'd see if there are other technologies in more popular languages with better licensing terms.
