Again, I'm not seeing the gap permanently on my check of your page. However, I do occassionally see the page on slow load not complete its collapse of the page frame for a short delay....and that is IFRAME issue. I can tell it's an IFRAME by right-mouse click and properties on the description section. You'll see the link for the page is to the new domain for IFRAME pages vi.ebaydesc.com host. The ebaydesc domain is where they are hosting the descriptions loaded into the IFRAME. Do that check outside the description section, and you'll see it's the old ebay.com domain.
This is an EBAY PROBLEM with IFRAME. Get ready folks, they are going to move it to the main site shortly with the new listing page design rollout that's been in beta for months.
Danno
Edit: This BLOG entry on September 26th at the eBay Developers site will cast some light on the subject. Note, the "Extra Whitespace" part of the discussion.
http://developer.ebay.com/community/blog/article/?categ...ract.html#Scrollbars