Patents, IETF and Network Operators

Hi, Network Ops folks use the IETF standards for their operations. I see lot of nifty things coming out from the IETF stable and i was wondering why those dont get patented? Why bother releasing some really good idea to IETF (i.e. open standards bodies) when the vendor could have patented it. The network operators can still use it as long as they are using that vendor's equipment. I understand that interop can be an issue, since it will be a patented technology, but it will always work between the boxes from the same vendor. If so, then whats the issue? Is interop the only issue because of which most ideas get released into IETF? I guess interop is *an* issue since nobody wants a single vendor network. Thanks, Abhishek