Try to go a little away from the base station, you'll notice. I have a 2 floor apartment and it was perfectly okay to use wifi on both floors w/2.2 software. Now I cannot get a connection on the other floor, so it must be because of 3.0 changed something.
I live in a 2 story house with a basement. OS 3.0 on 3GS in a case.
My router is in the basement and I am able to get my wifi in the backyard, front, garage, main floor and all up on the second floor without any drops.
Currently on the 2nd floor with 3/3 wifi bars bluetooth is also enabled, disable makes no difference.