This functionality was in etherpad, which was also YC-funded and also demoed their software with a playback of a pg essay.
While etherpad lives on as an open source project the original company/team was acquired by google and this resulted in google docs getting real time cursor movement and edits shortly thereafter (google docs originally updated via polling and often had collisions).
I think it's a shame that google never implemented more of the core ideas from etherpad, such as playback and contributor text highlighting. It's still the best online collaborative tool I've ever used. I had experiences writing letters to politicians in real time with dozens of anonymous strangers who we gathered via twitter, and collaborative grant proposal writing sessions that I can only describe as thrilling. It's also been fun to use etherpad to collaboratively take notes during conferences, and truly fascinating to replay and see how largely anonymous editors quickly start taking on certain roles without any prior discussion--one person gets very interested in fixing spelling mistakes, someone else gets really good at finding relevant urls for background information and links to slides, someone else just barrels ahead with whatever the presenter is currently talking about knowing that the others will fill in the gaps. A lot of the innovation happened in subset hardier, but etherpad made it way more accessible and this useful.
Etherpad deserved all the attention that google wave was receiving at the time because it really delivered on the promise of a truely flexible tool for collaborating and communicating more effectively than email.
> I think it's a shame that google never implemented more of the core ideas from etherpad, such as playback and contributor text highlighting
> Etherpad deserved all the attention that google wave was receiving at the time
I find your post confusing because I thought that Google Wave did have playback and contributor text highlighting.
I suspect that the reason Docs never gained these features was that Wave was supposed to replace it, but AFAICT Wave never saw the kind of user adoption it needed (probably due to its sluggish performance) and was killed off.
