Multiple Nginx instances serving up identical content (load balancing)

Hi All,

I was debating on posting this in Multi-DB Support, but decided to go here instead.

As I am building out a new WPMU environment using Multi-DB support, I'm unsure of the best (or most common) way to load balance across multiple http servers for multiple blogs.

Here's my example:

I have 10,000 blogs, and I all of them require high availability. This means if all content is on server A, (DB is remote) and ServerA goes down, then all blogs go offline.

Now, in order to manage HA, I want a load balancer in front of ServerA and I want to add a new server: ServerB. I need them to have the same content, WPMU configuration and access the same Multi-DB backend (remote).

Does anyone want to share their setup or experience? I believe that displaying blog content is very easy, but I start to think about plugin management, WP upgrades (say from 3.1 -> 3.2) and how I can manage this on a dynamic platform, and I start to think there are some key components that I need to account for.

Thanks for your input.