For some reason my post is empty, but fortunately I can copied it (since it failed once before):

The WiFi on my HD7 is always off. When I go the Settings page, it says it's "turned off", and then when I go into the WiFi settings and turn it on, it fails to find any networks. When I back out to the settings page, it still says "turned off". Also, the WiFi indicator at the top of the screen never turns on. Does this indicate there's a hardware issue, or is it possible something got messed up in software and I can fix it?

Have you tried turning your device off and turning it back on? I encountered this problem once (where I could not get the phone out of Airplane mode) and power cycling the device resolved the problem.

I'm having the same issue. Turning the device on and off has not helped. I even left it off for a whole night.

  Hi, monkeytheboy. If you're having the same problem that Hd7User described in the first post, and Wi-Fi will not turn on at all, then the first step I suggest is connecting your phone to your computer and checking for any available software updates through Zune or Windows Phone 7 Connector for Mac (if there are none, your phone is up-to-date). Once you've installed any updates, restart the phone and try to turn on and connect to Wi-Fi.

  If it still will not turn on, you will need to do a Factory Reset. This will delete your personal data, such as text messages, photos, videos, and music, so back up any important info before this step. To do the Factory Reset, go to Settings > about phone > reset your phone, and then tap 'Yes' and follow the on-screen instructions. 

  The Factory Reset will restore the software to factory settings, so if you are still unable to turn Wi-Fi on it may be a hardware problem. You will need to contact my teammates in Customer Support by phone, and they will be able to take the next steps with you. Please let me know if that helps!

I am having a similar issue.  The wifi seems to run very poorly for a few minutes after turning it off and on, then will simply stop working.  Turning the wifi off/on will sometimes clear it as will rebooting the phone.  The 3G connection always works, but there are downloads that require wifi in my podcast subscriptions.

The troubleshooting steps would be the same as the ones above for that issue as well, especially as you've already toggled Wi-Fi on and off and restarted the phone.

Let me know if you still have problems after trying the steps in the earlier post, rajczi! :)