Since I upgraded my Nexus One to Froyo, I have been having Wifi disconnection issues when the device goes into sleep mode. Almost 80% of the time I reawaken it, my data has dropped back to 3G and Wifi has disconnected.
Today I downloaded an app from the Market called "Wifi Fixer". A couple of tweaks to the settings and in the short period of testing since, my problem seems to be fixed. Anyone else having the same issues, could also try this.
I am using the 900/2100 version (probably the original T-Mobile stock), and I have tried all of the supposed fixes. Google have acknowledged this as an issue for *some* Nexi and are working on a fix with no ETA. In the meantime Wifi Fixer seems to have done the trick. Overnight for the first time in a long time, I was still connected to my Wifi network in the morning. This comes at a small cost though, as the battery use is slightly higher, most likely because the phone does not sleep as deeply as before.
I saw you updated the log report. No problems. It has to relate to the screen sleep state. I have seen the exact same behaviour as you - ie auto reconnect when woken from what I would describe as "light-sleep", a permanent disconnect when in deep sleep.
I have alogcat installed on my device, although i am not at home on my Wifi network at the moment. Tonight I may post some logs as it should be fairly obvious what the Wifi Fixer app is doing to alleviate the issue I have been experiencing.