I have to say I'm disappointed by this decision. I bought Sparrow a few months ago based on the understanding that Push would be coming in a future update. I don't believe they specifically said it would be free, but since devs cannot charge for updates and Push (or at least a periodic fetch) is a crucial piece of any mail client, I think my assumption that Push would be a free update was reasonable.

I'll continue to use Sparrow since it's by far the best mail client I've tried on my iPhone, but I think the developer needs to reconsider based on the implication that Push would be part of a future content update.