I'm from a physics background, so its not like I'm giving up lucrative work elsewhere...
As to jobs, I think it depends on the area you're in. Mathematical Biology is growing pretty quickly as a discipline, especially if you're into anything health-related. So I hope, anyway. At least it'll be fun to study...
I sure wish they'd let us know - that email was quite the teaser. I have another acceptance I'm very pleased with, but I really do love the Pacific Northwest.