Any build tools you get from the Raspbian repository should be set to automatically build applications that take full advantage of hard floating point instructions. If you find an instance where that is not true (and you shouldn't) then it would be considered a bug and we would work to fix the problem.
The only exception to this might be with some of the JIT interpreters which may only support armv7 floating point instructions which aren't supported on the Raspberry Pi armv6 CPU. In such instances we might not have to configure the JIT interpreter to not use hard float instructions. I would have to look over notes to see if we had to do this in some cases (I don't recall off the top of my head). However, with some interpreters such as V8 we were able to coax them to produce armv6 instructions so the code runs as fast as possible on the Raspberry Pi.