Since people were asking about Sandy Bridge IGP support, I've tried Magicka just for fun on my Apple MacBook Air under BootCamp with Win7 using a Sandy Bridge Core i7 CPU and Intel HD 3000 integrated graphics and it ran well. A little choppy when the screen gets busy FPS-wise, but that's to be expected. So I think the latest Intel HD graphics are feasible, but the older GMA generations won't have enough grunt to run this game. The upcoming Ivy Bridge IGP is expected to significantly boost graphics performance, so that should run at a fluid frame rate.
Disclaimer: I normally play on my desktop PC which has an NVIDIA GTX 480 and an i7 Extreme Edition CPU.