David Sparks posed a very good question regarding iCloud that's been on my mind since the announcement earlier today. He wrote:
My iTunes account is really old and affiliated with an older e-mail address. When I joined .Mac so many moons ago, I created a separate Apple ID, my .MAC account (which later became my MobileMe account). This has never been a problem. I’ve bought lots of apps, books, music, and video with the old iTunes account and the MobileMe account handles e-mail, calendar, and address book.
I have exactly the same issue. My iTunes account is under an old Gmail address that I don't use much, while everything else is under my MobileMe account, including desktop software purchases from the Mac App Store.
Although I haven't had any issues with this setup either, it has bothered me for a while. I have actually contacted Apple support on two occasions about this asking if I could merge both accounts. Both times I was told it wasn't possible. The first time was back in early 2010 and I had a very pleasant experience, even though I didn't get a solution.
The second time was terrible. The person that was on the case didn't read what I was asking and just kept pasting pre-written replies that didn't answer the question. It was a very un-Apple-like experience. After way too many emails going nowhere I just gave up.
Today, however, I'm wondering what's going to happen when iCloud is available.
Apple has to sort out this issue as I'm sure, as David is, that I'm not alone here. Anyone that signed up for iTunes years ago and then, some time after that, bought MobileMe, will be in a similar position.
In my case, assuming you can't merge two Apple ID accounts, I'll be left with the option of using my MobileMe ID and having to re-purchase all iOS apps (music should be OK from what I understand), or using my iTunes ID and having to re-purchase all my desktop apps. Neither of these seem like a solution to a very real problem.