WordPress MU

On the main page of mu.wordpress.org it says in the block on the features of MU:

- Unlimited users and blogs

Also, the description on that very same page reads:

"Ever dream of running hundreds of thousands of blogs with a single install of WordPress?"

Now from what I read, there is a built-in limit of 32000 blogs? That is far away from "hundreds of thousands" of blogs, and even farther away from "unlimited". Why is this advertised when there is that built-in limit?

I read by one of the developers that the way how wordpress.com fix this is: "There are multiple database servers, and between them the user database is split between 4096 MySQL databases. Slave servers are used to distribute reads."

That is hardly an out-of-the-box solution.

I am on a growing project which has 150.000 registered users. We want to allow these users to blog. If one out of five users wants a blog, we're already stuck with a basic installation? Is there a nice way to fix this, to get WPMU running for some hundreds of thousands of blogs?

I am also very interested in this, just listening. Good question wmostrey.

32000 is the hard limit for subfolders in linux. With a few modifications you can overcome this not too hard but you're not "out of the box" already. Soon enough (for instance if you want to run hundreds of thousands blogs) you'd need multiple servers to handle the load anyway, and start looking for scaling options.
The one used on wp.com is one of them, although i personally think it's quite complex.

not just quite ... it is very very complex

We just had a thread on this topic. Where did it go...