Can an LTM be connected to a Cisco FEX (fabric extender)?

Yes. I have a production pair of 1600s (LTM) and a 1600 GTM on fex. Set up with trunks - just like any other legacy switch.

Oh yeah... The reference Cisco forum above... Is relevant IF you're intending on running a SWITCH connection to a FEX. That is NOT supported (And in fact IIRC it shutdown the interface when you try and pass STP via them. or it might just annoy you till you shut it yourself from all the logging complaint about it).

Which find of forces you via the (v)PC route... (vPC if you want switch redundancy).

H