Arkie,
I had a look at the petition; not being a US resident or citizen, I probably should not sign it anyway, to avoid mudding the waters (or is it OK to add non-US signatures?).

But I am not sure I agree 100% with the petition anyway. I understand the initial argument and sympathise with it (don't limit the distribution of material that is no longer commercially viable after N years). But some of the supporting arguments are irrelevant, in my opinion (the fact that technology now provides faster and better distribution methods in itself is not an argument for curtailing copyright!). And the proposed solution, although it has some merit, could be improved upon. How about this option:

Don't ask copyright holders to re-register after N years (where N is of course less than the number of years provided by the statute) - but if they are untraceable then the distribution fees - where these are collectable by one of the agencies - should drop to 5% of the original fees. Where no agency is empowered to collect such fees, the amount should be paid into a fund for promoting and supporting new artists. In this way, the cost of using such old material drops to 1/20th of current, enabling freer access; and arts get a bit of a leg-up.

It remains to find a way to establish if a copyright holder is untraceable; something simple, I suggest, like registering the original enquiry, and 3 months later (or 12, or whatever) adding the work to an "untraceable copyright list" which can be used by all.