A rumor was circulating recently that Microsoft would be pushing a mini-ROM update for Windows Phone that would precede the big 'NoDo' ROM. It was speculated that this may be a test-run for the update but in fact, it looks to be a mini bug fix to ensure that NoDo and future updates are installed correctly. In fact, it sounds analogous to the Zune Desktop update that was recently rolled out for the same reason.
MonSmartphone.net is reporting that Microsoft France themselves have confirmed that an update will be pushed out to all users within in the next few days (we're actually told "today evening or tomorrow"). It's not clear if all devices are affected by this bug, therefore we might not see everyone get this update. Stay tuned.
Update: Confirmed by Microsoft US. All the details can be found here.
This first update for Windows Phone is designed to improve the software update process itself. So while it might not sound exciting, it’s still important because it’s paving the way for all future goodie-filled updates to your phone, such as copy and paste or improved Marketplace search.