There are so many opinions on this - the new, prevalent one seems to be that the only way to really learn the stride is to take your shoes off and run on smooth pavement - even the Vibram Five Finger site says this now.
The thinking is that if you run on soft surfaces, you will not learn to midfoot strike.
I dunno. I think soft surfaces teach you to pick your knees up, which is key. Hard surfaces teach you to run gently. Frankly, i just like it all. Did three miles barefoot tonight and felt like I could have doubled that. It's so much nicer now that it's warmer and the bottom of my feets aren't cold hardened. Just a great run tonight.
There are a million options for barefoot-style shoes now. Check some of them out. Altra, Vivobarefoot, Merrell, innov-8, etc.
You shouldn't be running in toe shoes on sidewalks either. Not at first anyway.
I use mine on grass hills or trails and usually only to do sprints. I also use them to work out in the gym, but thats for a different reason.