At DealBase, we've been testing Nginx with Passenger, and have mostly had good results. There are two issues that have come up, hopefully only one of which may broadly affect others.
<%= stylesheet_link_tag :standard, :cache => 'standard' %>
This worked fine for us under Mongrel, but it didn't seem to regenerate under Passenger after doing a deploy, even with a restart to Passenger. We had to do a second restart of Passenger, and then hit the server at least twice, if not more to see it get picked up.
Thanks to a tip from Engine Yard, one solution can be found on the overstimulate blog, where they detail how you can add a rake task that you call during deploy to regenerate those cache files. This is really even a nicer solution under Mongrel and others, as it will mean it doesn't occur during your first request.
The second problem seems confined to my MacBook Pro laptop (no problem on my MacPro tower). That is, I simply cannot get Nginx+Passenger to work. It installs fine, Nginx runs, but I get some odd permissions problem from Passenger:
2009/05/12 11:57:52 [alert] 19611#0: could not create /var/folders/7m/7m7ezMSTHdiBHz5bzVyNDE+++TI/-Tmp-//passenger.19596/control_process.pid (13: Permission denied)
2009/05/12 12:01:19 [crit] 19611#0: *1 connect() to unix:/var/folders/7m/7m7ezMSTHdiBHz5bzVyNDE+++TI/-Tmp-//passenger.19596/master/helper_server.sock failed (13: Permission denied) while connecting to upstream, client: 127.0.0.1, server: dealbase.dev, request: "GET / HTTP/1.1", upstream: "unix:/var/folders/7m/7m7ezMSTHdiBHz5bzVyNDE+++TI/-Tmp-//passenger.19596/master/helper_server.sock:", host: "dealbase.dev"
The first line of those two lines occurs when I start Nginx. The second happens when I try to surf to a page from my app in my browser (which makes sense given the first error :) If anyone has any suggestions on this one, let me know!