The ebuild just released into portage for 1.4.10 is missing the patch to apply changeset 990 from upstream, as discussed in bug #119050 (without which, cgi requests don't work if mod_fastcgi is loaded after mod_cgi - which is just how the lighttpd config files for gentoo work). You might want to add changeset 991 too, see: http://trac.lighttpd.net/trac/wiki/Release-1.4.10-bugs
Please take this in, it's a big fat pain in the ass to discover this bug on your own. Thanks, Joshua
1.4.10-r1.