Yeah, it's here at last! Read more about it on its dedicated page.

During the weekend we finally published the new processing service, which makes things much more scalable and stable. Processing is now done by an async service (but still within seconds), which also shortens the sending time, and dramatically decreases the sending timeouts. Besides this, we've also completed a brand new Postino service. I'm talking about a web-based, fully-integrated-into-Facebook Postino! That's right, it runs inside Facebook, at it allows you to use the stamps you already purchased from the iPhone. So, you'll use the iPhone version while you're on the go, and you may use the Facebook version when at home. We're pretty happy with the result: everything is done with AJAX, we've got frame animations and a powerful photo editor which lets you crop a photo or select whether the card will be in portrait or landscape orientation. The app will go live really soon (no later than tomorrow), and I'll post here the link when it's 100% ready.