<-- Master's degree in educational technology.
They're over-rated. Actually, a lot of those electronic "computerized" toys are crap. They've been with us for a generation - surely we should see a difference in results by the time the kids get out of high school, but we're not. The ed psych professor I have the most respect for uses the term "sugar popped." Those toys temporarily get kids ahead of the other kids, but they really don't lead to long lasting differences in IQ or ability. For the iPad, there are some apps that are decent; they make drill & kill fun. And for this, *maybe* I'd consider getting one for the kids. Once you get to the high school level, the vast majority of educational apps (at least of the hundreds I've tried) are crap; at least in mathematics & physics. For both, and especially for physics, there are an incredible number of resources online - various applets, javascript, etc - that don't run on ipads - that are an order of magnitude better than the next best thing I've found on the ipad. For example, look at the Phet site (physics educational technology from the University of Colorado at Boulder.) Won't run on the ipad; there's nothing that equals it on the ipad.
Furthermore, virtually anything you can do on the iPad, you can do on other platforms for far less money. A number of years ago, a lot of schools were pushing for a 1 to 1 student to laptop ratio. The results of that experiment are marginal, at best. I don't mean to be completely negative about the iPads though. They're a tool, nothing more, nothing less. In the hands of the right teacher - and with the right subject material, they can be very useful. I'm seeing a push in some schools to get iPads as a way to save money on texts. (Cue cynical) Yeah, right. Like the textbook publishers are going to let that happen. They're already taking steps to make it look desirable, but effectively not really save any money - the online textbooks are tied to one device; online textbooks expire after a number of years (a hard copy can be used for a decade for some courses without compromising educational quality (in most subjects.) At least, I don't expect there to be some monumental discovery that changes the face of high school algebra, geometry, trig, or most science matter (e.g., in the majority of states, virtually no physics from the 1900's forward is taught in high school.) The only definite difference is that students don't have to carry as heavy of a backpack home.