Here's a way to get your apps into alphabetical order automatically - all of them, except for the built in apps:
Go to Settings - General - Reset, and choose Reset Home Screen Layout.
Apple's apps will appear on top of your apps, on the first page, followed by the other apps you purchased. If you wish to get the built in apps into alphabetical order as well, you'll have to move them to their right place manually.
Hope that helps.