What day can we expect American weekly data to be updated?  Or should we just wait until NPD so the weekly data can be tied into more representative data..?

Im all for posting them weekly (if possible). Then we can have one set of discussion on the weekly charts, one on the NPD figures when released - and one on the (relative) accuracy of the weekly figures.

 Be nice if we can maintain a weekly "accuracy" figure, which measures how accurate our weekly figures are to the real (or NPD) figures - extrapolated of course, as NPD doesn't post weekly figures anyway.

I'd imagine weekly figures would be posted... uh... weekly! 

Otherwise, while it may be nice to have a comparison to the NPD stuff I don't think that's quite possible with them breathing down this site's neck.  Additionally, while the NPD numbers are considered accurate, they're also only an educated guestimate and should be taken with a grain of salt as well.  Unless you get data from all sources, there will always be room for error.