What is Solidcoin?
From what I've seen (and I'm sure some of this is incorrect or incomplete)...
It is an alternate cryptocurrency which started from a slightly different philosophical platform than bitcoin. Unfortunately, in addressing some of the issues (real or perceived) with bitcoin, it managed to introduce some new issues which had already been solved.
When these issues were pointed out to the developer/creator, he became defensive, belligerent, offensive, and combative. So much so, in fact, that the solidcoin mining pool at btcguild was shut down by that site's administrators. Sometime around this point, someone attacked the currency (a 51% attack I think?). Mining was stopped, the chain was rolled back, the code was magically reformulated (it's magic, at least until the source code is released), and about a month later (just in the last few days, actually) was relaunched as "SolidCoin 2.0!"
I'm sure there were a few people like me who tried mining of the 'new' solidcoin for a day or so to see how quickly they could generate some coins, but it looks like most people are working hard to either (a) get the hell out and divest themselves of everything solidcoin-related, or (b) trading frantically, trying to make a bit of cash as a cryptocurrency day trader.
In summary, SolidCoin 2.0 is another flawed cryptocurrency with some interesting ideas, but doomed to failure mostly because of the overwhelming arrogance of the lead developer.