Read this article on Liam's blog. He interviews Royler Gracie blackbelt Eddie Kone about the new app about to be released, covering all kinds of exciting techniques for maintaining, attacking from, and defending the mount. Unlike many iPhone BJJ apps, you don't get partway in and then discover additional fees and costs to proceed with the lessons. The techniques are taught in sequence from particular positions so you can map out attacks and counters from each.
There are about 16 techniques, each lesson is around 5 minutes long, and there's additional bonus material at the end.
The app will be released in late March-early April. More info about it is on Eddie's blog here.
And if you'd be so kind, when you read Liam's interview please tweet, facebook, and google it by pressing those tiny buttons at the bottom of the post.