Other than that, I think it looks like a great idea (love the name) and could have a decent chance of going somewhere (assuming enough small biz firms are sophisticated enough to use it).
Edit: or maybe the plan is that the ad exchanges (e.g. Rubicon) do the vetting, since they're in-between leanmarket and the publishers?
For richmedia, the publisher (website owner) just accepts to serve a Javascript snipped, which most of the time request more Javascript from places the publisher has no control whatsoever. And it has to be inlined on the page because that script uses document.write like crazy.
because of that, the script has total control of the page.
That's why there's no rich media in most free email providers. Yahoo is the only one but they render the ad in an crossdomain iframe and force the ad to behave via a richmedia api
The system sounds pretty slick, and if does what it says it will, I think their UI will go a long way towards helping them gain traction with the smaller firms.
If it truly makes things as easy as it wants/claims to, it should find a pretty solid base of users fairly quick.