Polar opposite in the sense of openness, yes. But very similar in the sense that there is a focus on services (content-oriented hubs in WP7, Conversations, Contacts etc on Maemo) instead of apps. Interesting Ballmer quote: This angle might be a big opportunity for Maemo/MeeGo as well, the infrastructure with things like Telepathy and Tracker is already there. Think of how Skype integrates with our N900s, where it on other phones is "yet another app"