(please don't answer that, just answer my first question!)
Obviously .PSD support is not included in this first beta, I'm betting it is a top-requested addition for the commercial release. But only Adobe can tell us if this will happen.
To answer your question about files with layers, the first beta exports TIFF files. I did this, sent the file to PhotoShop, added an adjustment layer and saved the TIFF without flattening.
Back in Lightroom, the layered TIFF shows up with the changes I made. LR's tools seem to work on this layered TIFF (just quick experimentation, no guarantees).
If this can be done with TIFFs, then I'm sure the same wll be true for .PSDs later on.
But be clear - all of this happens on the TIFF copy, not on the source RAW file. Also, versioning isn't here yet, hope that gets added to the commercial release, too!