I practice what essentially amounts to pair programming very regularly. On the other hand any kind of TDD seems to be mostly moot for projects I work on. I assume this is because most of my projects involve disparate components with continuously changing interfaces and just getting together works better than producing interface specification that is complete enough to base any tests on (and to be clear: it's not about two people being in same room and each hacking away at his component, but about both working alternatively on each component).

I'm somehow surprised that this even works well with pairing of programmer and hardware engineer, but that requires management that believes in their engineer's skills (rapid iteration and hardware tends to get very expensive very fast) and programmers that have meaningful insight into hardware.

On the other hand projects I work on are probably not very representative of anything as most of them are weird :)