The site seems to be up again now. A few things:
I noticed on their license agreement page
the following statement:
Each journal sent to Index Copernicus becomes a property of IC. IC has the right to get over sent journals to whoever without any notice to publisher/ editorial office/ owner or any institution owning and/or cooperating with a journal.
I'm not sure what the second part of that statement means, but the first part should definitely be worrisome to anyone who wants to retain rights to their journal. Maybe it's just an awkwardly-translated sentence, but on the face of it it's a copyright grab.
Also, I'm trying to figure out exactly what is needed to send information to them, but I can't find any instructions. They have a web form that can be filled out, but I can't see any other way to send data to them automatically, which would be the only way you could develop a plugin for OJS to work with them. OJS does support OAI-PMH for example, so presumably Index Copernicus could use this widely-understood and supported protocol to index journals that sign up with them.