Most of the 0k uploaders are just a minor bug, indeed, since they are shown by the gui, but the LimeWire core already skipped those, so the overall upload abilities are not reduced.

However there are actually two kinds of 0k uploaders, there's the kind I described above, which is just a minor bug, that actually has already been fixed in the development code. The other kind is caused by unresponsive remote clients downloading from you. It will take LimeWire a couple of minutes to identify those and to drop them. - However, there have been rumors about malicious servents that start downloads and reduce the download speed almost to zero, to take away upload slots. I don't know if those rumors are true, but they might be.

The next beta will be out in a few (two or three) weeks, I think. The LimeWire devs are currently working on some major improvements to the gnutella protocol.