I've seen it a few times when it passes over the UK, it's quite visible on a clear night, moving very quickly.
A few years ago we saw Discovery approaching the ISS, which was quite a cool sight. Two very bright points of light moving at apparently the same velocity.
I managed to get tickets to see Discovery's next launch (STS-133), currently scheduled for the 23rd of Feb. I'm quite excited!
It will be one of the last Shuttle launches; after that, only Endeavour is scheduled 1(STS-134; then Atlantis is scheduled provisionally, but STS-135 has not been confirmed yet).