Trainspotters, eagle-eyed bloggers, and tech detectives of all stripes have had a field day with last night's iPad commercial. At the very least, we got a pretty good look at some e-book prices, ranging from Ted Kennedy's True Compass: A Memoir ($14.99) to Three Cups of Tea: One Man's Journey to Change the World... One Child at a Time by Greg Mortenson and David Oliver Relin ($7.99). All gripping reads, for sure, and all more expensive than Amazon. In addition to all that, TUAW has made note of a New York Times button, possibly to bring up NYT bestsellers in the iBookstore. Delving deeper into the UI, a look at the Pages iWork app has revealed a button labeled My Documents (where have we heard that one before?). But Oscar night is not the only place for iPad leaks: according to a tipster named James Barcellano, close viewing of the iPad keynote video has revealed an "Open In..." button during the viewing of a PDF attachment in mail. Perhaps this is an indication that the device's file system will be a tad more open than we were expecting. Or maybe not! You know how these things go. One more pic after the break.