I have 7.60 Technology Preview 3 and know of a page where it scrolls too far to the right, I'll try that out and report back.
EDIT:
On the page in question, Mozilla 1.7.3 with a screen resolution of 1024x768, there is some horizontal scrolling.
However the same page when viewed in Opera 7.60 TP3, shows no horizontal scrolling, but the right border of the box consisting of Google text ads on the right side of the page, is chopped off.
It is a preview (beta) release though and I haven't read anything to indicate when 7.60 will be officially released.
UserAgent: Mozilla/5.0 (Windows; U; Windows NT 5.1; en-US; rv:1.7.3) Gecko/20040910