You're asking a crowd that is heavily biased towards Haskell, what they would use C++ for?  You should expect many answers to be of the form, "Well, if Haskell doesn't work, I'll try generating C or C++ from Haskell."  :)

Which means, people here often see other languages as target languages for code generators.  Which is something I think is pretty cool.  But, getting back to your question...

If I were considering writing something in C++ here are some of my considerations:
1) Is the thing I'm writing known to be easy to solve in C++?
2) Will writing it in C++ instead of, say, Haskell give me access to a developer pool that is superior for the task?
3) Will dealing with the very few drawbacks of laziness, in particular lazy IO or space leaks from laziness, end up dominating the development effort?
4) Is it a work related project?
5) Am I just making a prototype or executable specification?

I put (2) and (4) up there because I think it's important to consider who you'll be working with.  I can't really get way with using Haskell much at my day job because I'm the only one there that wants to use it.  The company has to deal with the code I create even if I move on.  Also, programming is hard regardless of how cool your language is.  So it always seems wise to work with the sharpest set of programmers that you can.  Sometimes that means picking a particular language.

It's also important to think about the merits of the languages themselves, such as (1), (3) and (5) point out.  If you're prototyping, Haskell is light years ahead of C++.  Then again, optimizing C++ programs, while tedious and error prone, is understood by far more people than optimizing Haskell programs.  Laziness can be unpredictable.

I like Haskell a lot and I'd bias all my answers to the above 5 towards it, but C++ is also a very cool language.  It's just cool for very different reasons than Haskell is cool.

Heh.  Yeah, it can be ugly, but it's also very powerful.  The template system is Turing complete as you may know.  Boost and Loki are two good examples of some of the cool things you can do with C++ if you really work the template system.

Ah yes, even you're thinking about code generators.  It's a very common way to think in this community it would seem.

Jason