I don't typically use smart collections, so after reading your post I thought I better try it out. I found that the smart collection feature really doesn't have the same interface as (for example) itunes does.
At any rate, to do what you are describing this is what I did:
I clicked on the [receipts] collection.
I then clicked on the [browse] icon at the top. This drops down two windows with a list of categories on the left window and their corresponding values on the right window.
I then scrolled down and selected [date] from the left hand window which populated all my receipts dates in the right window.
I then scrolled down the right hand window and highlighted all dates within 2008 (that is 12 fields ~Jan 08 to Dec 08).
I then clicked on [save] and this prompted me to create a "smart collection." I named this collection 2008 receipts.
I hope this is what you are looking for. I don't think this method is as clean as how itunes is set up and I'm not for sure if live updating actually happens, but it did put all my 2008 receipts in one folder. Please let me know if this was or was not what you were looking for.
Robert
