The other day, my friend Geoff reported an iPad fail: an inability to scroll within a frame for a hotel login page, and similarly an inability to scroll in a Google Reader frame.
Geoff's as expert as they come, with computers in general and with Apple products too. He waited in line to get his iPad. But he couldn't figure out how to scroll these frames: scrolling by dragging a finger just scrolled the overall page, not the frame.
The solution is simple: scroll with two fingers in parallel, within the frame.
This is actually documented in the iPad user guide, which is bookmarked in Safari on iPad. One of the perils of a device this easy to use is that nobody reads the manual!
The interface is still quirky: no visible scroll bars even suggest that content overflows the frame. This does save screen real estate, precious on a 9.7" screen. But it can definitely lead to overlooking content, if you don't know that there even is anything to scroll.