the copyright shldnt be a problem. just post a notice saying ok to use when you post the presets.
here's the deal. let's say i download one of steve's filters. i've got the 9 to 20 presets that come with the thing, but no doubt, steve has others he didnt publish and is willing to share these. or, vice versa, i've downloaded the filter and made 20 of my own and want to show steve. seems a fairly natural thing. the person posting simply says somewhere in his post 'these are ok to use for non-commercial purposes' or whatever he wants to allow. it's not a big deal, i wouldnt think.
this also might be an interesting way around the freebie re-selling of textures. presets posted in the forums would NOT be covered by the FF EULA's. they would be copyrighted by the authors, however. therefore, re-sellers wouldnt be able to use these without permission of the author.
but, it gets really ugly-tricky at the same time, since, if someone did take the presets and put them with the filter, who's to say that the other person didnt make the preset? lol. aint this crap fun
and, it's probably all moot anyways, since i think the presets much be part of the filter's .ffxml file.
If wishes were horses... there'd be a whole lot of horse crap to clean up!
Craig