I built this. It's not really supposed to be a Twitter/Stack Overflow hybrid but it does incorporate some of those things with more integration to come. It's supposed to be Hacker News (as you can obviously tell) for .NET devs since that community is very fragmented.

If anyone has any feedback, I'd love to hear it.

Also here are direct links: http://managedassembly.com and http://managedassembly.com/twitter for the .NET Twitter stream I launched Sunday.

Gray-on-gray-on-gray with big bold fonts don't make for good readability.

Very true. I'll work on it.