It is a pack of ten curriculum resources for teachers and students to explore by combining the real world with virtual content using a web cam.
Some of those demos are brilliant. The Geiger counter and physiology ones seem to provide real value when coming to teach such subjects. On the other hand, I really don't find any benefit of using the English application over a computer game. In a sense LearnAR is showing how gimmicky and how useful AR can be at the same time.
For another perspective on using AR for educational purposes, you should really check out Gail Carmichael's blog. Since she's doing her PhD on this subject, she has blogged about some very interesting concepts.
As for LearnAR, you can learn more about it on James Alliban's blog.