Moments ago, the team released a system update (aka Dash update) to Xbox Live. Over the next few hours, when you sign in to Xbox LIVE, you'll receive a prompt to accept this mandatory update. What's in this update? The only thing this minor release will do is prepare your Xbox 360 for the wireless guitarsthat are being released in a few months.
No new features beyond this wireless support are included in this update. As usual, we've got some new features planned for later this year as part of our biannual release cycle.
So why wouldn't they just do a title update. Hm, interesting.