While adding running balances to the summaries I discovered that the numbers didn't add up. After some trial and error I fixed the errors. The biggest problem was that many of the e-check PayPal transactions were erroneously marked as "cleared" when they should have been marked as "uncleared" - this mislabeling is frustrating but I know how to spot this in the future.
I am now very confident in the accuracy of these data.
http://meta.wikipedia.org/wiki/Wikimedia_PayPal_donations_for_2003
-- Daniel Mayer (aka mav)