Rackspace’s new AppMatcher marketplace is intriguing for a variety of reasons. For one, it smacks of the Microsoft Windows Azure strategy of bringing together users and ISVs under a single roof. The strategy is that a big enough user population means everyone will want to participate. And while you’re experiencing the Rackspace goodness, why not host your application there too, or maybe offload other workloads like you are the one being delivered via SaaS. Where Rackspace misses out, though, is in guaranteeing developer dollars — if it had its own platform, apps would have to reside there. As is, it must hope it can lure ISVs into becoming paying customers.