Surprisingly there are few video podcasts (vodcasts) teaching 7-12 math. At videomathtutor.com you can find 8 free lessons in basic math and algebra. Any iKid can take it on the go after a quick iTunes download to brush up on some skills.
iTunes U contains mainly college material podcasts. Although there are many teachers putting valuable math video content on line, the future of edtech seems to be mobile driven.
Economically, m-Learning materials are best downloaded and carried from docking stations. Only 6% of people have used Wi-Fi in public places. This could be due to data security risks and the inverse relationship between speed and mobility. Paid services over 3G networks require unlimited data plans to optimize quality.
