Safe to Delete Mobile Applications I back up my iPhone 4 and iPad 2 to iCloud.
Is it necessary to keep my Mobile Applications Folder?
There are over 12GBs of space being used by this folder on my Macbook.
Could it be thrown out?
I would be careful. You may be backing up to iCloud, but syncing locally with iTunes. If you DO NOT sync your Apps with iTunes, you can throw it away.

Personally, I would keep it and maybe just delete some of the old apps you no longer use.