The new version of the update rolling out over-the-air fixes the Wi-Fi issue. If you downloaded the previous version, you'll have use Samsung Kies to update the Android software again.
Here's the word from Samsung:
"Earlier this morning, Samsung began releasing an over the air software update allowing Galaxy 10.1 users to upgrade to Android 3.2 while also resolving a Wi-Fi connectivity issues some Galaxy 10.1 users experienced following a previous software update. For Galaxy 10.1 users who are experiencing Wi-Fi connectivity issues and are unable to reconnect, the new software update may be downloaded and installed via Samsung's Kies desktop app."