I really like the idea you have presented. My idea would be to create a few sp's/jobs with different amounts of days until expiration since applications need to manage their passwords with more than 2 days notice. Something like a 30 day, 15 day, 10 day, 5 day, and 2 day notification. THat would give them more time to plan and make the change before it becomes critical.
Just an idea. Thanks for sharing yours!