In the official statement by the developer, they stated: ”Harmonix is restructuring our organization to bring it into alignment with our current product development plans. Unfortunately, this means reducing the number of full-time staff. We sincerely appreciate the work of each and every one of these employees. Harmonix is working to ensure that those affected are well taken care of as we make this change.”
Harmonix is currently working on a Nintendo 3DS version of Rock Band, and have promised that future projects and downloadable content for both Rock Band 3 and Dance Central are unaffected by the cuts.
Whether that remains true in the future is another question, we imagine.