The Kobo will do this automatically, because calibre writes directly to the database.
On the Kindle it is a little harder, because the database is hidden -- but since you have the PW1, either you are jailbroken or you can -- and it just requires another step or two. Once you have it set up, you shouldn't have to think about it anymore.
Just install
[GUI Plugin] Kindle Collections and follow the directions listed.
It has gotten easier/faster now that barsanuphe released librariansync (a Collections Manager alternative).
Do note that there are other differences between Kindles and Kobos, my favorite difference is the one where the Kobo spends a few hours processing every time you add a bunch of books.
Dunno why they are the only ereaders out there (that I know of) which don't just let you read the book immediately...