The malware poses as an Adobe Flash Player update but in reality its designed to log a user's browsing history, in particular their Google search queries within Firefox. This information is uploaded to a hacker-controlled server.
Havent came across this, but as market share grows, it is only a matter of time before FF is in the fireing line. The hackers and exploiters usualy only go after the targets with the biggest penetration within their markets. IE has long been a target, Fireox is closing the gap and is now its self becoming more of a likely target.
Things like this could be make or break for Firefox. It will be vital for them to be seen to make the right response.