GLBSE looks very interesting. How safe is it? Is it well established? How runs it?
Security wise, it's VERY secure, using cryptographic keys instead of password logins, we're beyond password security. I'm the guy who runs it(I've been around for a while), on behalf of several investors(including myself).
We've been live for... oh nearly 4 months now (I think) and have had no breakins or losses.
glbse.com itself is fine(with regards security and trustworthyness) , the biggest issue is finding the right share to invest in, currently they're all quite high risk ( the shares that is) and people have already lost bitcoin, although quite a few have made some also.