Well, I'd argue that you *can* psuedo-hand-sort all your books, and traverse them fairly easily... any time I have books that are in a series, I rename the file to something like "Dresden 01 Storm Front.ePub" and set the title to, "Dresden 01: Storm Front" That way, when I go look at books in my library, all of the books in the same series are grouped together, and in order. That, and I have a separate folder on the disk for each author, and is working well enough for the 500+ books I have on my KT right now.
Don't get me wrong, I'm looking forward to additional functionality too! Although I could really care less about sorting, I would be very interested in filters - show me *only* books from author X, or in series Y, etc., until I tell you otherwise. Lists are a bit more problematic - when I first got the KT, I tried using the favorites list, but on device it is fairly slow to add/remove books from it, and I'm not a fan of the Kobo Desktop or Calibre Desktop tools (love the calibre command line tools, though!). Ah, well, need to figure out how to do this by making updates to the database, I guess