Purchased Apps on more than one iphone w/multiple iTunes accounts
What you do is the following, you can put purchased apps on up to 5 computers.
Lets say you have XYZ app on your phone & you want it on your wifes phone.
Launch your wifes itunes account, connect your phone, authorize the computer, go up to file & select "transfer purchases from phone to this account". It will then put all purchased songs, apps, etc. in her account. From there you connect her phone & select what you want to transfer.
Cheers