Despite some positive reports in September, it looks like you won't be able to merge Apple IDs.
You can, however, set up iPhone, iPod Touch, iPad, Mac or PC to use two different accounts for iCloud and purchases:
iPhone, iPad, or iPod touch:
When you first set up your iOS 5 device, enter the Apple ID you want
to use with iCloud. If you skipped the setup assistant, sign in to
Settings > iCloud and enter the Apple ID you’d like to use with
iCloud. In Settings > Store, sign in with the Apple ID you want to use
for store purchases (including iTunes in the Cloud and iTunes Match).
You may need to sign out first to change the Apple ID.
Mac:
Enter the Apple ID you want to use for iCloud in Apple () menu >
System Preferences > iCloud. Enter the Apple ID you want to use for
store purchases (including iTunes in the Cloud and iTunes Match) in
iTunes > iTunes Store.
PC:
Enter the Apple ID you want to use for iCloud in Control Panel >
Network > Internet > iCloud. Enter the Apple ID you want to use for
store purchases (including iTunes in the Cloud and iTunes Match) in
iTunes > iTunes Store.
Note: You can switch the Apple ID you use for
store purchases at any time. However, you can only change the account
you use for any iTunes in the Cloud features once every 90 days. See
this article for more information.
