Inkling is a publisher of etextbooks that makes interactive textbooks for the iPad. According to the NY Times both McGraw-Hill and Pearson are making investments in the company. Total amounts were not disclosed.
Pearson will make two dozen of its textbooks available and McGraw-Hill will add its top 100 college titles and some medical and reference books. Inkling hopes to have 100 textbooks available by the fall.
More info in this NY Times Bits article.