I'm totally confused by the apparent consensus sentiment going around on this. I adore Instapaper. I think it's unbelievably well done, I use it, and I don't have plans to look elsewhere.. that said, I can't say I worry or get sad about people who develop competing products.
Seriously?
It's ridiculous to react that way. First of all, I find it patronizing. Marco's really fucking good at what he does. If it turns out that what he does is easy enough for someone else to swoop in and do better easily, then what he does isn't all that interesting. I doubt that's the case.
Second... fucking of course. This is how it works, and how it's supposed to work. We're all consumers first, producers second. As consumers we benefit from this mechanism CONSTANTLY, and the things we consume are directly responsible for making the things we produce possible. We all got Facebook from Myspace from Friendster... Look at your car, look at your appliances, look at anything in your life. The ability to completely rip off shit and do part of it a little better is where much more innovation comes from than individual giant Big New Ideas. The folks that stay on top for prolonged periods of time are folks who capitalize on that are able to do that internally instead of resting on their laurels, and frankly Marco has proven that tendency as well.
[Edit] Sorry, further. The point isn't what Instapaper (as a product) is today, and this is exactly why small companies are great. It's what Marco is. When I go down the street and buy fresh pasta from the place that's been making it for longer than I've been alive, I'm not buying a product.. I'm investing in a relationship... A relationship that I can trust to deliver me compelling value on an ongoing basis. It's one thing to swoop in and build a product that looks very much like one that's on the market (only free, or whatever). That's not interesting to me. You haven't really accomplished anything valuable. In fact, it's easy to argue you've literally sucked value out of the world. It's another thing to replicate the ability to deserve people's trust that you'll continue to deliver value in new ways... even if the original source for your inspiration is gone (and especially if you were to blame for it).
TL/DR: I ain't scurred.
[Edit] Downvote explanation anyone?