That looks like an R2 feature, and we don't support Windows 2008 R2 on the web servers yet. But I don't think it's an extension that we would expose/offer anyway, as it kind of defeats the purpose of the application pool time out. We don't necessarily want an idle application to start every time the app pool recycles. If that was commonly used it would have a negative impact on server performance. Great for a dedicated server or VPS, not so good for shared hosting.
