Meego will be free, and I don't think the question is whether Nokia will allow the N900 owners to get a chance at it, this has already been guaranteed. N900 will run meego period, there will be an N900 binary and the N900 device itself is completely unlocked with root access etc. You can run whatever OS you can hack on to it. The thing that you are looking for I think, is if Nokia will provide a finished consumer grade Ovi branded Meego with niceties such as Ovi maps, Skype commercial application store etc.
I am 99% sure that that will not happen and that if anything consumer grade appears it won't be spearheaded by Nokia but by the 'community' with maybe a Nokia assist here or there.