app-vim/udev-syntax-20051016 is not able to automatically switch vim to mode for udev-rules files, it seems to have the old name of the rules-file hardcoded.
The filename is no longer udev.rules, but /etc/udev/rules.d/*.rules Perhaps one can match "udev/rules.d"
Created attachment 106376 [details, diff] Modifiy detect-routine to work on newer udev-filenames This patch changes detection to test for existance of udev/rules.d inside the path.
Created attachment 106378 [details, diff] Ebuild-Changes
Fixed in CVS. Thanks for the report and the patch.