Main Content Width on GooglePages
The width of the main content window in this single-column layout is 585 pixels, so the widest of AdSense banners—the 728×90 "Leaderboard"—cannot fit even on this page. In fact, it wouldn't even fit inside the entire #container DIV of a GooglePage template, which is only 718 pixels wide.
The full-width AdSense banners thus cannot physically fit on any GooglePage created using GPC, leaving manually uploaded pages as the only option for "Leaderboard" banners. But seeing how even the second-largest banner is dominating the look and feel of this page, perhaps, it is actually best that the widest one won't fit.
A technical aside. There is no actual sidebar in this standard single-column layout. So a left sidebar is emulated by a 170 pixels wide DIV, which is floated in the top-left corner of the main field. The width of this main field is 405 pixels—the same as the width of the standard main column in a 2-column GooglePage layout.
The sample ads at the bottom of this page and the following paragraph are displayed inside the main single-column field. The procedure for adding the AdSense code was the same on this page as was described in AdSense tutorial
for the 2-column page layout.
Mozy AdSense Test
An unintentional AdSense experiment is running here for historical reasons. The original version of this page included the GPX-Files review of Mozy Remote Backup. The review since then has moved to its own Mozy Backup review page, but the backup-related ads continued for a couple of days. Google does indicate that AdSense can indeed take some time to be updated. Part of the current experiment involves using the AdSense section targeting mark-up.
Incidentally, Mozy is a great free remote backup service. See the GPX-Files Mozy review for details, or use this direct link to Mozy
and receive a sign-up bonus for a total 2GB+256MB of free strorage.