On the K2 if you go up to the top line of the Home screen. and push the 5-way to the left, it gives the choice of Personal Docs, Subscriptions, Books, All my Items.
So far, the only personal items I had put on the K2 were a couple of text files which I had dragged over from my Mac. These were appearing in with the books. However, I then plugged in my K1 to the USB port and dragged into a folder on my computer some files which had previously been sent to Amazon and returned to my K1 via whispernet. Then I ejected the K1, plugged in the K2 and dragged these files into its document folder. After I ejected it, these files all appear in my Personal Docs if I choose to have the K2 sort that way. These are all files which show the "author" as my e-mail address. I thought that was the clue, only recognizing personal documents which are tagged with your e-mail address.
However, it turns out that documents e-mailed to Amazon for conversion to be sent back to the K2 just land in your Books, not in Personal Docs. Thus there is a flaw somewhere. Does anyone have a solution? Please comment if you do.