iLife doesn't appear in "Purchased" after installing ML on a registered MacBook Pro
I just went through this same problem. Originally I called Apple and they said that iLife was linked to someone else's account so I could not download it. Upon further research I found the above mentioned method.

1) In Finder, click on the Go menu.

2) Click Go to Folder.

3) Enter ~/Library/Caches/com.apple.appstore/

4) Drag adoption.plist to the Trash.

5) Restart and see if they appear in purchased items.

I actually chatted with apple first and had them reset the account.  They did this, and I should have been able to get the purchases within 24 hours using this method.

It did not work, I chatted with Apple again (chat session). They took me through the above step, with still no result. After not being able to access it, Apple gave me a redemption code through the app store. All in all it was not too big of a problem and I now have all of the factory standards.