Starting work on Similar Surface modifier. First patch contains the entire structure, excluding the actual binding and deforming code within the main modifier function. There's quite a bit to do to add a new modifier, so if that was bugging you -- it's not an issue anymore. Just apply this patch, put in the magic bind/deform code and away you go!
I guess this is no longer needed (as you said via blog post, mdef improvements implement this functionality anyways) :)
However, perhaps it might be a beneficial tool for new developers to post a generalised version of the patch (i.e. without the specific binding bits) as a tutorial on adding a new modifier if there isn't one already. Perhaps with suggestions to replace all the names in the patch before applying to source...