Hi Yuri,
I know those sorts of models may sound like baby stuff... however, in the interviews the thing I kept hearing about repeatedly was execution time. If that is the case, it could very well be that the underlying models are just simple, it's just that they need them to run extremely fast. Of course, I could've been mislead since these were just interviews - the interviewers certainly wouldn't have spilled the beans on what they're doing in such a context. And since my resume plays up my programming skills, there's a definite selection bias going on.
I should also warn you that some of the interviewers for these companies didn't even know what an MFE is! There also seems to be plenty of demand in this field for people with electrical engineering backgrounds in signal processing. I'd be surprised if any MFE curricula covers that.
As far as your question on what you get asked about - presuming my experience is typical, expect questions on your background in statistics, a lot of C++ questions (multithreading is a plus, STL is de rigeur), and questions on whether or not you've used R/SAS or something similar. Plus the usual brain-teasers.