Jim Hoing over at Sourcelink says they've got a new service in beta right now that may help publishers get around the whole email deliverability thing. It's called SNAP (an acronymn chosen by someone who I guess had no idea that it's already being used by the Society of National Association Publications. Hey guys, check Google prior to picking a product name next time).
Anyway, it's one of those desktop items where when there's news, users get a "flashing news bar on their application". Right now about 600,000 people get weather alerts that way.
I've seen pitches from several companies over the past 18 months with ideas of this ilk. Forget email, we'll stick your announcement right on the desktop, or in one case during the desktop power-on procedure. The main problem is that invariably these require a download. Average consumers hate, hate, hate downloads. They take too long, they might be viruses, their IT team yelled at them last time they downloaded something, it breaks, whatever.
Until you get your app stuck on desktops by the PC manufacturers so they ship with it installed as a default, you probably won't make much progress.
There's a real idea there somewhere: Weatherbug??