Compatibility between 802.16 and 802.11

No. Not even close. There's talk of using SDR (software defined radio) methods to create a universal client radio for laptops and PDA's, but at this time, it's science fiction. Note that it can be done.
802.11b/g has a considerable number of inefficiencies (mostly timing) that 802.16 solves. Re-introducing these inefficiencies, on the same frequencies, is both expensive and clumsy. Most of the WiMax stuff will move to the new 3.6Ghz band anyway, where there's no 802.11, so compatibility may not be as important as perhaps in a laptop or PDA that needs to talk to both.
Ethernet to Ethernet should work just fine. You might wanna throw in Bluetooth, IrDA, and various fiber optic interfaces for a truely universal conglomeration.
Question: What problem are you trying to solve?