Internet Explorer is not supported. There's a feature detection running at the start page which blocks off browsers who don't support all feature. No released IE supports background gradient's - so they are all blocked. IE 10 will support them, and by the speed browsers iterate nowadays (thanks to Chrome starting that trend) I have hopes that it's release won't take too long.
CSS3 Pie (http://css3pie.com/) adds linear gradient support to all versions of IE. Still not 100%, but it's enough for a lot of people.
it has no support for color-stops in gradients, but your right - would be enough for most people. but since the audience are web-designers, for whom 2 color-stops would be a limitation, it's no option.
I have never managed to use css3pie without it totally messing up all my other CSS.
I've used it on one site and it worked fine there, but admittedly that's a tiny sample size.