So, what do you need to be an effective rigger in SR4? Skills, hardware, cyberware?

And how do technomancers fare as riggers? Do their strange electromagnetic powers give them any special bonuses?

from what i have gathers you need a comlink with a sim module and a control rig implant. in fact the control rig is optional but gives you a +2 when becoming the vehicle.

You might want to also check out the Shadowrun 4: Hacking and Rigging sticky thread at the top of the forum.