[update] I got some unite services working now from any browser, must have been a glitch earlier -- feel free to leave a comment on my fridge :)
Opera announced that they would "reinvent the Web" today -- having spent some time going through what was announced I'm not sure they managed to reinvent a whole lot.

So what happened? They announced a beta of Opera Unite, with what they call a "Web server on the Web browser". Trying to make my way through the marketing speak the best description I found was in the FAQ: "share the content directly from your computer rather than loading it and sharing it through a third-party server".

This is essentially P2P technology, a term many companies now seem to avoid like the plague for its association with illegal filesharing through bittorrent (which is a whole different issue). Opera has some services that you can install in their browser that run over a unite:// protocol (file sharing, a fridge message app, media player, photo sharing etc.). According to what I've read this is supposed to be accessible from any browser, though haven't been able to get that to work -- partly because the service seems to be overwhelmed.

That might sound a bit strange a P2P service getting overwhelmed, isn't the whole point that it goes directly from one computer to the other? Well when you run a service like this it need to go through a server to resolve the connected clients so they can continue further data interaction directly between themselves rather than passing through the server. This is I assume also why you're required to have an Opera account and sign in to that to run any of these services.

I really like the idea of what they're doing, and P2P, client-to-client, UDP or a host of other names it gets advertised as is definitely the way forward. Not necessarily for services like they currently demo on Opera Unite but certainly for live audio/video streaming and other situations where bandwidth throughput is still a real issue.

Where I think they got it wrong is integrating this in the browser, this is not a technology that should run on a client software level. I see browsers as simply rendering web content, they should IMHO not play an active role in the data connection flow of web applications. The marketing slogan "reinventing the web" is fundamentally flawed in that sense, they seem to have create a separate channel of services that run client side in the browser and facilitate P2P through their Opera server. It doesn't seemt to be about "the web" whatsoever.

For what its worth, I think Adobe is working on a better solution here with Stratus -- bringing P2P to Flash content (for more information check out this video on Adobe TV). With the RTMP specification getting opened up yesterday, I hope they'll do the same for this RTMFP which would enable open source alternatives to Flash Media Server to facilitate these P2P enabled Flash applications. The key benefit here being that it gets served from the web server runs cross-browser and cross-platform and its not using a browser specific protocol or going through an Opera server to establish the connection.

In half a decade's time this will hopefully all be standard functionality on all common web servers but for now its interesting to see various solutions come up to make this happen.
Please bear in mind, these are just my initial thoughts and observations of what Opera announced and what I could figure out from reading the site. I'll be happy to review this again in a few weeks when I've had a chance to try it some more.