This change is mostly directed at our Price Guide subscribers. In the daily guide file that you download, you get CSV lines like this one (split across two lines for the blog):
"4007","Cars","Nintendo DS","Racing","785138361123", "2009-03-06","3","8.84"
Indicating that Cars for Nintendo DS is a racing game with UPC 785138361123. In the seven days prior to March 6, 2009 we had 3 price sources and the median price was $8.84. The first number in that column is VGPC's product ID number for this game. Even if we fix typos in the UPC or the product title, this ID stays the same. It's included in the file to give you a stable reference number for each product.
As of today, you can also use that number to easily locate the VGPC product page for that game. Just visit http://vgpc.com/game/4007 where "4007" is whatever product ID you're interested in. By making a Firefox bookmark keyword for this URL format, you can easily bring up the full price chart for any game in the Guide.
For those interested in a similar Firefox shortcut for generic VGPC searches, we posted instructions for that last year.