I thought the problem may have been related to the fact that I updated to iOS 5 on my phone first and it prompted me to create an iCloud account on there that became tied to my apple id.
When I installed the Lion update today and it told me to move my MobileMe account to iCloud, I figured it would simply take all my mobileme information and download it to my computer for use in my new iCloud account, or otherwise let me designate the target iCloud account.
That's when I ran into the problem everyone here is reporting. About 45 minutes ago, I was finally able to move my MobileMe account to iCloud, so that disproves the theory that the difficulty is related to multiple accounts. I think the server was simply overloaded. Keep trying and eventually it will work.
However, once I completed the process, it was only to find that I ended up with another new iCloud account!
What's worse is that this was the family pack master account that I migrated. I ultimately completed the migration according to the instructions and then when done, I went back to system preferences and disconnected from iCloud. It allowed me to keep my contacts and warned me I would lose my calendars and other data. I took the plunge anyway, figuring I could manually restore important calendar items later.
As luck would have it, nothing was lost or deleted. Everything stayed on my computer as I would hope.
Then I reconnected to iCloud using my brand new iCloud account from earlier in the day, the one I had created on my iPhone and which is tied to my apple id. All my information got synced up to iCloud from my computer. I verified it by going to iCloud.com
So all's well that ends well. My apple id and my icloud account are now one and the same, and I have all my information syncing as it should.
For all of you encountering difficulties, I strongly encourage you to consider the hassle you will have to deal with should you end up with an iCloud account that is not connected to your apple id, which is what WILL happen if you move your MobileMe account and that isn't already connected to your apple id.
Instead, don't bother moving anything. Just make sure all your mobile me content you care about is on your main computer and create a new iCloud account that is tied to your apple id.
After you have done this, you can use Apple Mail to move all messages from your inbox, drafts and sent folder under your MobileMe account into the corresponding folders in your new iCloud account (or just keep both email accounts if you desire).
Anyway, the point is, I see no value in moving your mobileme account unless it is already tied to your apple id. If that's the case, then do it. if not, then stop worrying about the server being down. It's not going to be helpful in the long run unless you actually want two independent accounts (iCloud vs iTunes purchases)