Well, useless isn't the proper term, but this more PR related move of nVidia is useless for most of the users of CUDA and even OpenCL. I prefer *BSD UNIX as the platform performing my scientific work and lack in the ability to produce GPGPU based code, even using LLVM 3.1 right now as the OS's backend compiler. Using Linux for those tasks is the only way to get out of this dilemma - but as the former poster stated - you need still closed source libraries to compile proper machine code for the target hardware.
So, what is nVidia aiming for? Since I see only a very narrow corridor of usefulness of their move, this is a PR action and therefore considered "nasty" in my opinion. They fake the fact being "open" by opening something that is completely inappropriate. As long as there is no widespread, broad platform-spanning solution for their CUDA or OpenCL, even this PTX backend is questinable. May those who listen to nVidias "words" be wrapped up in this lullaby song of "OpenSource" blabla.
I made last year my experiences with another promis of being opensource from PathScale. Since then, nothing useful has been emitted although they claimed having something just to be ready for being published.
