Those are all ad-hoc.. As soon as the tablet is rooted, you can hack it to see ad-hoc networks, but as of now it will not see any ad-hoc wifi networks such as ones created with mywi, and pdanet.
I realized when tethering, it only works if making it an open hot spot, no password... it's an android thing.... I had the same result with my sony tablet using my Nexus s, and my friends iphone for tethering