I recently switched from the iPhone's native mail app to Sparrow. It's great. I've also heard great things about the app Fantastical as a replacement for the native iOS calendar app. I'm considering coughing up $5 for it. The less native iOS apps I use the less I'm tied to iOS as a platform. If Android offers the same apps I've adopted to replace Apple's core utility apps, the cost of switching away from iPhone is significantly lower.
As hardware becomes more and more of a commodity, Apple should focus on delivering best-in-class software. Otherwise, the app ecosystem they've built might in fact lead to people jumping ship to use their favorite apps on other hardware.
And here's a bad-pun alternative title: "Put the app back in apple"