The base reason for the greenish tint is fluorescent lighting have a green tint that we don't perceive, but cameras, film or digital, pick up quite nicely.

I have the SD950IS in my pocket at all times (titanium body, yay), and it's the second (lost #1 at a MV Show) and it's quite worth it.

The A480 is $111 on amazon right now, and the main difference I can see is it uses AA batteries rather than the Li-ion battery pack of the PS-SD line.