This question came up a lot because people feared that the Olympus camera business will be shut down or acquired after the US$1.5 billion scandal that tried to hide investment losses came up. The company is most certainly under huge stress still, and the entire board (which included many members of the executive team) was implicated in what happened. After restating their financial numbers for the past five years, undergoing an external audit (though by people appointed by Olympus), and generally admitting to what happened, the actual fraud is now mostly behind them. The issue still present is clean up and restoration, and settlement of a few outstanding cases. Sony invested in Olympus to help them with their financial position, and at this latest update, I’d say that Olympus is beyond the scandal.
The problem is that the camera division has not shown a clear and consistent profitability for quite some time. While the current financial numbers are decent, Olympus is still not profitable at the level of the big three in cameras.
The worry when you buy into a system is that the system won't be around forever, thus upgrade and updating options will go away. Unfortunately, the risk of that isn't zero for any system. The scandal increased that risk for Olympus aficionados, but only minimally. Plus, Panasonic shares the m4/3 mount, so you could always just replace your Olympus bodies with Panasonic. So while there's still some risk, I judge it to be a very low risk overall.