The reasons, suggested by people familiar with the companies, are myriad, although the major sticking point seems to revolve around payment.
BBC's Daniel Danker alluded to this when I met him last week at a briefing for the new iPlayer; namely that the broadcasting giant requires the service to be available to every Xbox owner and not just those with a gold subscription.
Obviously, the BBC's licence fee includes payment for the iPlayer, but Microsoft is apparently keen to ensure that additional media services on the Xbox stay at the Gold subscriber level.
That two major corporations cannot come to a quick agreement is not surprising; but that those talks began back in 2009, and have still not come to any kind of fruition is certainly a source of frustration.
With the Xbox 360 in the latter part of its cycle, the likelihood of a deal is beginning to wane. Would the iPlayer on a silver subscription attract new people to buy the console? Probably not in any major amounts. Would it persuade current owners to buy Gold? Obviously not if it's not a requirement for access.
There remains a constant burble of speculation that each Xbox update will prepare the way for the on demand service, but you won't be blamed for failing to hold your breath.
Obviously, the BBC and the UK market are a fairly unique proposition; the US does not have an equivalent broadcaster that is funded by licence fee so there is no problem with other on demand packages being part of the Gold subscription band.
But, the BBC is a vital part of any on demand proposition in Britain, offering a ream of high quality and popular content, and any service which does not offer an iPlayer option is going to suffer in comparison.
The Xbox is not alone in this; Sky's lack of BBC VOD content is a persistent bugbear for many, especially given the success of the service on cable rival Virgin Media.
You would hope, regardless of the chance of an Xbox 360 iPlayer, that Microsoft has at least taken note of the problem for its successor – whether it be the Xbox 720 or something else.
That way it can factor in the iPlayer on a subs-free service and use it as a reason to upgrade your hardware rather than do without and pale slightly in comparison with its competitors.