Ben Brooks, writing on The Brooks Review:

Instapaper has now gone version 4 and Marco Arment has been kind enough to let me test out this new version. I can say that this new version is, without a doubt, fantastic. Arment is fond of saying that Instapaper has the most generous update policy (every update has been free) and I would argue that the only software company more generous is Apple with iOS. But, why — why wouldn’t Arment charge for these fantastic updates? Let’s let him explain:

There’s no good way to charge for updates in the App Store. Maybe Apple will add this functionality in the future, but they don’t seem to care so far. Maybe they’ll add it when they want upgrade pricing for the next version of Aperture or Final Cut Studio. But I’m not sure I’d charge regardless. I get a lot of goodwill from my customers by continually improving the product that they bought months or years ago, and that goodwill helps spread the word and drive new sales. I know I charge a “premium” compared to many other apps, but I want people to feel like Instapaper is a ridiculously good deal. In my book Instapaper is certainly a “ridiculously good deal” and that may sum up Instapaper 4 perfectly. Read Ben's entire review for a complete overview of each new feature.