There are a few hold ups right now. RIM controls the 'switch' to turn this feature on, although the infrastructure is currently in place through the PAS system. Carriers want to have ultimate control over which OS's can go on their devices, so the current system in place and the popularity of using non-certified OS releases is under scrutiny and some carriers are pushing back to RIM for some changes. This may lead to restricted OS updates based on your Device and Vendor IDs (i.e. - for an AT&T-branded device, only AT&T updates will be available).
The latter portion has caused quite a stink for IT departments wanting to deploy a uniform OS version hosted on their own network, which was the understanding of how this would work beginning with BES 4.1 SP4 (and SP5, which still doesn't have complete configuration and functionality). The infrastructure has been in place since last Summer, though.
Lastly, OS 4.5 has only recently been launched by one or two carriers. In the coming month or two, a definitive compromise will need to be made between the carriers and RIM. I think we'll see something definitive by then.
__________________ In the beginning the Universe was created. This has made a lot of people very angry and is widely regarded as a bad move.
