Yellow light means its on standby. It gets hot, but wont burn down or anything. You have your Wii set on the standby mode to receive msg's from Wii users. If you switch it off it should go red.
I know that, it just surprised me for a bit that it was hot, I would've assumed the darn thing would've switched on the fans or something...
@TriniWyatt, I know they get hot... I'm thinking I should probably get my PS3 in my bedroom where there's A/C and it can be happy
Bottom line is, maybe Wii sport resort did some update or something that might have affected normal wii sports and because not too many people use it for 4 player tennis anymore nobody has noticed(?).
Either way, I plan to get the new super mario wii sometime this week, and its PS3 equivalent (not sure if this a stupid statement) Little big planet, I'll check for you online when I get them.