The Raspbian project is a rebuild of Debian for the Raspberry Pi. adama did some benchmarks that show the improvement in going from ARMv4T with soft float to ARMv6 with hard float: http://www.memetic.org/raspbian-benchmarking-armel-vs-armhf/
The page says that there's a 4-10 % improvement on integer programs and up to 40 % on floating point programs. It's hard to tell the new instruction vs pipeline influence and if the baseline is soft float or softfp/VFP based.
-- Michael