While Rock Band 3 has not yet been released, it is "design complete and on the final path to 0 bugs, GM and distribution," according to Teasdale. "I want to be able to help drive the vision and direction of a game," writes Teasdale. "But at the same time be hands on and physically implement and iterate on the low level of making games in a more substantial way than time affords me when working as a lead on multi-hundred person titles."
This is not something that can be done easily as the "lead on AAA titles with 200+ people on them". At Twisted Pixel, Dan will work on a "ridiculously cool new project" and he describes the position as the "holy grail of game design positions - I'll get to contribute and help drive the direction of a well funded and supported new title with a close knit superteam, while at the same time being hands on and able to directly impact all aspects of the game."
Additionally, another Harmonix developer, Rob Weychert, has also left the studio today. The departures appear to stop at two, but perhaps we'll see more studio members leave now that Rock Band 3 is "design complete". Shacknews will keep you updated with any additional personnel changes.
Rock Band 3 will be released this holiday season for the PlayStation 3, Xbox 360, Wii, and DS.
Thanks to Shacker 'ratsofatsorat' for the tip.