Dotdeb’s packages of Nginx 1.2.4 are now available for Debian 6.0 “Squeeze” (amd64/i386). They fix some minor bugs, please take a look at Nginx’ official Changelog before upgrading.
Please also note that Passenger has been upgraded to the 3.0.17 version.
As usual, if you want to know which module has been included in each Nginx flavor, you just have to look at this document.