We have what I guess is the forerunner of this one by Baby Jogger: http://www.babyjogger.co.uk/performance.html
I'd thoroughly recommend these - you can run on any terrain. I've run on everything and my daugher who is now 2, but has been in this since she was little over 6 months old, is very comfortable - she loves running with me.
The wheels come off with ease and we stick the whole thing in the boot.
We did buy a generic snugglebag to fit this for the winter and also a rain cover (you just cannot trust the British weather...). 
