I would like to second this suggestion. I am using the Windows Live application on my Tilt 2 Windows Mobile 6.5 phone for the Windows Live mail syncing and push features. However I have both an @live.com address and a Windows Live Mail custom domains address, and can only set up one at a time. The other I have to check via the mobile web site.
I would love it if Windows Mobile OS or the Windows Live application supported multiple Windows Live Mail accounts! KevinHarder.com