Dotdeb’s packages of Nginx 1.2.1 are now available for Debian 6.0 “Squeeze” (amd64/i386). They fix some bugs and enhance the IPv6 support. Please take a look at Nginx’ official Changelog before upgrading.
Please also note that Naxsi has been upgraded to the 0.46-1 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.