You can pretty consistently get the phone to somewhat "forget" it's association with your wifi if you do the following....
1) Use the built in Power Widget to turn off wifi, and turn on. Sometimes when I do this, it still knows the wifi exists, but will not grab an IP. The only way to "wake it" so to speak is to enter wifi settings, which for some reason gets it to refresh.
2) Leave your home network range while on a voice call, and then return while on the same call. The connection will not resume, and at times it forgets the wifi networks saved settings. It will detect other access points which it considers "in range" but your home access point will be shown out of range.
There are certainly some open issues with the wifi.