[Plugin Show Unread Comments] Not working in 3.0 – alternatives? Workarounds?

I love the Show Unread Comments plugin*, based on Smart Unread Comments. It looks like neither of the authors are updating the plugins. I’ve spent all morning searching WordPress and Google for a replacement, because I think this plugin really helps readers keep track of ongoing discussions. Can’t find anything like it (that isn’t also broken).

Anyone know of anything similar that’s hiding from me? Or feel like taking a look under the plugin’s hood to figure out what’s broken now?

*Didn’t link to this one because the developer removed the page. The other one I did link to is very similar – good enough for my needs.