Does he have any claim to fame beyond very elaborate trolling? I've been trying to figure out what's up with him recently.

Popescu is waging a pathetic little personal war against FetLife [1]. He's a textbook example of a self-deluded crypto-narcissist who, if there's any justice on this earth, will see his comeuppance. People like him always do.

[1] He's been scraping the profiles of young women (specifically) and posting links, names, and hometowns on his blog. Yes, as technologists, we know that this kind of indexing is trivial. That's no reason, as a decent human being, to terrorize innocent people.

Wealth.

Most of the publicly known early adopters don't spend as much (or any) time trolling about (and getting trolled) on IRC.

http://search.bitcoin-assets.com/?q=from%3Amircea_popescu

Possibly some people have been exposed to mircea through hearing about his insane quotes such as:

  The most you can do, after having been educated/raped, is picking the what and the how for other, later, virgins.

http://trilema.com/2014/patriarchy-is-a-thing-because-nobody...

Or they have read his Guide To Beating Women blog post:

http://trilema.com/2011/cum-se-bate-femeia/

Or perhaps they have read how his site for betting with bitcoin screwed someone over for about $7,000 in bitcoin:

https://bitcointalk.org/index.php?topic=339544.0

Do we know how much he's actually worth?

His >50% MPOE[1] stake is at least 1.4 million coins (valuated by the last trade).

If you're skeptical of numbers on webpages (c.f. "EmptyGox"), MPEx's trivially traceable addresses[2] currently contain around five thousand coins; tracking down the rest is left as an exercise for the skeptical sleth.

[1] http://mpex.ws/?mpsic=S.MPOE

[2] https://www.walletexplorer.com/wallet/MPEx.co

Maybe I'm reading it wrong but according to that there is ~10m shares outstanding at a price of 0.00028btc per share. Doesn't that make it worth around 2800 btc not 2.8m?

We're both wrong. One billion shares, half of which he can't sell:

  CL-USER> (* 1/2 (expt 10 9)
              (parse-float "0.00029087" :type 'rational))
  145435

Oh, and who the hell is paying 50 btc to open an account at mpex?