I don't know where all those iPads are, but i see PLENTY of
iPHONES on public transit, but at most i see 1 iPad per day on a train and almost never on a bus.) When i say PLENTY of iPHONES i am saying clusters of about 3 to 6 on any end or middle of a MUNI LRV. Whereas last year and in 2009 i observed things, i might have seen only 2 to 4 iPhones on either END of a train, and sometimes the same number on BART. Nowadays, it's either end AND the middle. On buses, I see maybe 4 or 5 max.
However, as for Kindles, I see 2-3 a day on either of those transit vehicles. As for seeing iPads in Borders before they shuttered their downtown SF locations, I would see 2 to 3 at a time starting from release date.
There are a couple of coffee shops i visit, and they are mostly or almost exclusively ithis/ithat although 20% might be generic win-based PCs and virtually NO win-based nor Android-based tablets -- yet.
Interestingly, this individual (I cannot tell if it is a man or woman, honestly) who USED to carry and dotingly use an iPad in the morning for several months and lug a laptop or book tote now only carries a reader.... Kindle, and NO lugged electronics. So, that person appears to have NOT upgraded to the iPad 1.5, er, umm, two.
At any rate, Apple execs and designers must be wetting their pant and spraining their wrists when the look at the iPhone -- and to some extent the iPad -- signal blobs on a real-time wall display. Sure, there are maybe 5x as many non-Apple phones on a transit vehicle, and a very packed train of some 200 people must have some 30 or 40 iPhones in each car, but those non-Apple phones are fragmented across different OSs and styles of phones.
iPads, however, seem to suffer from price and glare and random if not increasing new reports of thefts (at weapons-point) of Apple products in SF. One or 2 people were even home-invaded and relieved of their goods. Kindle might be less tempting a theft target, I suspect.