Here we go again!
Immediately after upgrading to OS 4.3, my WiFi connection drops a couple of times an hour. I tried all of the published fixes from the last OS upgrade WiFI problems with no success.
I can reconnect by "forgetting" and reestablishing the connection or turning Airplane mode on and off.
I had the same problem with the last OS upgrade and I returned that iPad to Apple and got one with the OS before that. That worked fine until I "upgraded" to 4.3.