Do any of the current crop of HDV cams have uncompressed audio instead (or in addition too) of mpeg1?

By definition, no. HDV doesn't provide for uncompressed audio. The HVX has it, but it's not HDV. And the forthcoming generation of AVC-HD cameras can offer it, but again they're not HDV.

Now, with that said, there was once upon a time some confusion over the HD100, as it was apparently engineered to record HDV-compliant compressed audio but also simultaneously recorded uncompressed audio in the DV audio track portion of the tape. So there was some discussion as to whether you could rewind the tape and capture audio-only, so you'd capture in two passes: once for HDV video/audio, then rewind, put the switch in "DV" mode, and capture again to get uncompressed PCM audio (but no video).

I believe Steve Mullen tried it and the results weren't encouraging; maybe it was only one track or maybe the audio was overmodulated, I don't really remember.

yeah, I was hoping for more of an in camera second track solution but no dice. Oh well that's why G-D made separate sound systems.