we face similar annoyances.
The reason for not scrolling is IMHO very simple.
The IFRAME Content is actually created to its full extend - even though you might have specified the width and height.
Means: even though you do only see a portion of the IFRAME it is actually there in full size but those portion that is not covered by your w/h is just not visible (BUT IT IS THERE).
Therefore it is very reasonable that it just CANNOT scroll.
iPad has become a very disenchanting experience - most of the software (Mail, Safari) is littered with Bugs of all sorts (crashing, not displaying, not willing to work etc.).
They(Apple) should react real quick and not wait till FALL to release patches.
Maybe there might be a way to create the IFRAME differently, since I read a post somewhere where somebody claimed that he was able scroll an IFRAME.
If anybody out there can do so please post the URL.