last year or two I've seen some very impressive platform independent GUI's built with java.
Not for R. One could argue for Python in the same light, as well.
I fully agree. Platform-independence is one thing, freedom another. R is free-as-in-freedom-software, so it would really be a pity not to use a powerful free-as-in-freedom-language to build R-GUI(s), be it Python or another one. This being said, any project to bring R on any computer in the world is to be praised, but please let R as such not be contaminated with a language that doesn't come out of the mouth of a healthy gnu... acolyte of service, Tobias