Yes, you're right, I forgot that Instapaper had a free version for a long time. I took out the "in private beta" parenthetical because I thought it was a way to include a link to the beta rather than as a way to specify how long "for now" is. I can see you're interpretation now too.

I will say that the big difference between Instapaper and Spool is that while Instapaper did have a free version from the get-go, it was feature limited. It's going to be hard trying to balance the feature sets between the two when their users are already used to having the whole thing for free.