Yeah, it is weird. But the wifi doesn't turn off when it goes to sleep. It's weirder than that. When I wake it up, the icon in the system tray isn't the wifi icon (the bars), but the icon for a wired connection. It shows connected at first, but the first time anything tries to hit the internet, it changes to the limited connection icon. Then I have to turn off/on the connection (swipe from right and click wifi, or tap the internet connection in the system tray, then turn wifi off/on), and then it will connect. I'm guessing that it may have something to do with having the Windows Phone SDK installed, and the emulators using Hyper-V, but I don't know for sure. I haven't felt like uninstalling/reinstalling Visual Studio, because that is always such a pain, with all of the VS add-ons that are installed, too. Getting it all back the way you had it is always such a pain. For that reason I haven't tried, and opted to live with it so far, hoping each month that it will be fixed by patches. Alas....
EDIT: Oh, and yes, I have the i5 256.