Installing Varnish with nginx, Passenger, and Monit on Ubuntu 8.10 intrepid:
http://trevorturk.com/2009/10/22/installing-varnish-with-ngi...
It's a bit out of date now, but basically still applicable.
Also, here are some packages for Sprinkle, which is an alternative to Chef that I like:
http://github.com/trevorturk/sprinkle-packages
Varnish is not installed by the default example, but look in packages/varnish.rb and you'll be able to sort it out.
Go go gadget Varnish!
But, this appears to be a new blog from Posterous, with this submission being it's first post, and it comes to HN just after Posterous had some, well potentially negative press about their traffic.
Am I off base in asserting that this blog post is a marketing play? And if this isn't their first blog post, please let me know of my grave error (and down-vote me accordingly)
Edit and follow-up: This blog has been around for a while, so I guess I'll sit back and relax. However, I'll still stand behind the marketing assertion.
The usual failure case for this is that a cache node goes down for awhile, misses some invalidation messages, then comes up and starts serving (stale) traffic again.
This case isn't so bad if you keep your TTL low, and have cheap page revalidation.
We use Delayed Job at Posterous for things like this. Resque works too.
I am currently going through your VCL to take some ideas for improvement. Thanks for posting that.