That would be one way to do software installs. However, I think that method will cause an installer to run under a different security context than the account that is logged in. (I've run into problems with that before with program installers that only install per user. It really depends on the application installer.) I'll investigate that option a little more though.
Currently, when we have a situation that required admin rights for installation under the security context of the user that is logged in, we have to that user out, login as an admin, grant that user admin rights, logout, have the user log back in and install the program, and then we would need to log back in to remove the admin rights.
I may just write something to do this as a desktop app. After thinking about it a little more, it's possible to query a computer the currently logged in AD username. That user could then be added to the local admin group. A logoff would be required. The admin rights for that user could then be removed using a computer startup script or through my previous idea of a scheduled task (or both).
Of course I may be making a relativly simple issue more complex than it needs to be.