OK. Yes, but no.

You can try basecamp which is online or writeboard which is a module within basecamp.

Now Voodoopad Pro has websharing, but it says it’s only local network. I’m sure that this can be extended to the outside network as well though, but I don’t think it’s on the fly updating. I could be wrong though.

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I lied.
Coccinella does what you want.