Core i7 and 16GB RAM is what we tested on. It's a reasonably sized machine for a sophisticated developer. (And only sophisticated developers should be playing with pre-release software.)
I don't know if it would run on less because we didn't try. I wrote that because I know it WILL run on that, and I don't know if it will run on less. I upgraded from 8 to 16 GB before I even tried.
If you find you can get by with 8 GB or 12 GB, or a smaller CPU, please share it on the developer channel, or let me know and I'll post it.
RE: Dawn 1.0 Released