The new Hotmail interface includes a built-in SMS alert feature that will ping your phone whenever a message matching one of your filters arrives in your inbox. Tech-Recipes walks you through setting up the alert and filter for very specific email.
Hotmail's built-in functionality makes deciding exactly which messages arrive at your phone more guided and easy to pin down. It's another consideration in how Hotmail actually stands tall next to Gmail, though those with more filter/search kung-fu qualifications will probably prefer Gmail's powerful selection tools.
Hit the link for a visual walkthrough of the Hotmail SMS alert setup.