这年头有了pubsubhubbub之后刷新闻的速度越来越牛逼了。TechCrunch才报道了Source: Google Is Acquiring AppJet, The Company Behind EtherPad，刚在Google Reader里按J之后，第二则新闻 Confirmed: Google Acquires AppJet, The Maker Of EtherPad就出来了。

Etherpad是一个真正的实时协作在线写作程序。比Google Docs的多人协同创作牛逼之处在于它几乎是real-time的。

Really Real-Time

Other "real-time" editors like Google Docs work by broadcasting an updated copy of the document to everyone every 15 seconds. This creates a noticeable lag that gets in the way of collaboration. You start editing something, only to find 10 seconds later that someone else deleted it.

Etherpad updates every copy of the document every half second. This 30x increase in speed changes the experience completely. Your edits hardly ever clash with other users'. So you work confidently instead of tentatively.

Why doesn't Google Docs update every half second like Etherpad does? Because it's really, really hard. We're fairly experienced programmers, and to make this work we had to solve problems that, as far as we know, no one had solved before.

反正Google Docs的多人协作是15秒刷一次，Etherpad是1秒刷2次。估计Etherpad是通过增量comet实现的（更新：Operational transformation。comet的ARQ也不好做。。。）。但是这个说起来容易操作起来的确很麻烦很hack。

AppJet是YC S07提供的种子投资，当然News.YC上少不了对这场好戏的讨论。搞笑的地方，几个老板都是前Googler：

A number of ex-Googlers are AppJet executives, including CEO Aaron Iba, CTO J.D. Zamfirescu, and COO Daniel Clemens

这次被Google又收购回去了。。。真囧。。。。。

购物狂Google扼杀了不少技术创新啊。n年前扼杀了Jotspot，做出来了个废品Google Sites，现在又把Etherpad团队收买了去填Google Wave这个坑，天知道Google Wave最终会是个什么样子。