I've been watching Piwik for a bit (they do analytics software, we do analytics software) and I believe they set aside their scaling work until after version 1.0.

I would love to see an independent open-source analytics company with a services / enterprise business model, along the lines of OpenX for ad serving and the pre-acquisition MySQL. Not so sure the economics justify it, though.

Actually, I've been thinking about doing this for a while -- this thread convinced me to put up my MVP to see what happens.

While I'm waiting for DNS to propogate, here's a sneak peek: http://img.skitch.com/20100831-kf41k4mpc4gd612jyhdcbtyxgh.jp...

edit: it's now available at http://dashboard.io -- would love any feedback I can get. :)

No (speaking from experience - we've had no end of issues with piwik and larger websites)

Could you quantify 'larger'? Just wondering at what point this starts to have problems.

Don't know if this relates directly to the question about scalability, but the main site is not loading for me, nor is the demo site.

It looks like the tracking script hosted on demo.piwik.org is slowing the main site down.