Gotcha, no worries. In any case, you've got some of the same problems to solve that SitePoint staff does vis-a-vis programming contests.* The trick is it needs to be meaty and interesting enough to get good answers while being constrained and limited enough for someone to tackle in a reasonable amount of time. Limiting it to .NET definitely helps as it levels the playing field quite a bit--some things that are very easy in .NET (eg--XML Serialization) are difficult on other platforms and vice-versa. You also need to sort through different people's idea of what is a good contest. IE--is data interchange cool? Or should we focus on client-side pizzaz? Finally, scoring is a pain--really, really difficult to normalize in any meaningful way.
* I should note here that I wanted to have one throughout the whole period I was on staff here, I just didn't have a good idea about how to do it so said grand scheme was never executed. But I did ponder quite a bit so this is a bit more than idle chatter.