The last couple of days I'm trying to finalize the first release of patch-o-matic-ng. Everything seems really close now. A lot of patchlets available for 2.4.x however are missing for 2.6.x kernels. Maybe the biggest and most important lack is for all conntrack/nat helpers.
The reason is that the semantics for those helpers have completely changed. They now get fed non-linear skb's by the conntrack core, which in turn means that they all need to copy the skb payload into some temporary buffer in order to search for some particular string (e.g. PORT command).
The conntrack core should definitely provide some function that is able to look for strings within a packet. Need to think more about this.