I’ve been using border-radius (and the webkit/mozilla versions of the spec) in my interface work for sometime now. While I haven’t gone so far as to include shadows or gradients, I do make occasional use of text-shadow as well.

I’m a firm believer in graceful degradation, and if you’re careful in not over-exerting the design (layering up with gradients and shadows and all that hullaballou) you can end up with a relatively consistent style across browsers.

The example here has some very extreme variances, but that’s hardly going to be the case if you use these techniques with some forethought rather than a demonstration.