I'm just a user, but I had the same problem when I was running Gingerbread on my HTC Legend. Now, there aren't really any proper drivers for that on Gingerbread, so it was done ad-hoc. When I updated to ICS on the TF101 it lost the ability to connect to ad-hoc hotspots. Installing a ROM that uses Froyo fixed it.
I think Prime users faced the same issue, but managed to enable ad-hoc support. Root on the tablet was of course needed.