I sometimes copy the XMP files since my workflow uses XMP exclusively.
If you need to just transfer a single tag or colour class (e.g. you did the selecting and editing on laptop on jpegs for quick upload, and later need to tag the same photos but raw on your primary computer for archiving), you can use PM command in menu Edit/Save Selection to export a simple text list of selected files. It's easy to just use any text editor to replace all occurences .jpg with .cr2 in the text file, in case you need to go from jpegs to raws.
On the second computer, you can just import this text file using Edit/Load Selection and it automatically selects all matching file names in the current contact sheet.
Kirk, while we are talking about this, would it be possible to simply have the Load Selection open up a file open dialog, where you could select multiple text files, instead of first opening the Choose one or more files to load selection from dialog (I don't know though if all file open dialogs on all OSes support multiple file selection)? Or is the additional dialog intentional to let people know they can select multiple files?
Of course, it would be nice if the Save selection/Load selection allowed for a tick box to save the tag, rating and colour class (and possibly crop, although with crop rotation that would entail more data and more parsing of the files I guess) inside the text file as well (as a simple comma delimited list perhaps).
