there is l7-filter 2.19 that supports 2.6.25 kernels. http://sourceforge.net/project/showfiles.php?group_id=80085
i'll be so happy when people move to l7-filter-userspace so I can drop this package. Myself and upstream would be glad to hear reasons why this is not acceptable.
added 2.20. thanks Nebojsa Also added l7-filter-userspace-0.10