I recently did a research paper on iPads and Special Education. However, some of my research and findings can carry over to general education students.
For a majority of students, using the iPad for educational purposes can increase their attention span and focus on tasks. What is not clear is always the "why?" Some feel this is just because it is "new" and kids will flock to it because they see it as a "toy." Other students, especially those with autism, can relate more to electronic devices since they often lack the social aspect of life.
I am all about the gadget and my kids have access to many electronic devices in the house. Depending on what they are being used for, I can sometimes see that their behavior starts to get a little worse -- not willing to do things or go places, gets short and lippy, wound up, disruptive, or all of the above. Of course, this is where parenting comes into play and these devices need to be limited and/or removed from the situation.
However, I can see both the good and bad in them.
BTW, my 10 year old son is getting an iPad 2 for Christmas and my 8 year old son is getting an iPod Touch. There are TONS of educational apps out there. Additionally, there are organizational apps to help with scheduling, homework assignment, and other time sensitive tasks.
IMO, the iPad is not all about games. Yes, my iPhone and iPad has games on it in the event I let them use them while we are out to dinner, but I will monitor their usage after Christmas and make sure that they are not abused with a high usage of non-educational stuff.