This is quite an old answer, but just to add a couple of remarks which might be interesting.
First, the "180 steps per minute" metric is attributed to Jack Daniels, a known running coach which was training runners for the 1984 Olympics. In his reports, he stated that of the 46 olympic runners he studied, only one took less than 180 spm (176 spm). On the other hand, he noted that he never met a beginner runner in his career who ran over 180.
So there are two important caveats here:
The 180 spm he mentions is not a target number, it's actually a minimum number (after discading that one "176" outlier) at which these professional runners were running, at "olympic paces" (around 6 meters per second, or 2.8 minutes per km).
It's impossible to make a fair comparison of olympic runners' cadences with those of beginner runners. I.e. an olympic runner might keep a 3 min/km pace at 200 spm, while a beginner runner might not be able to run faster than 6-7 min/km, so it's not surprising that the cadence would be lower for beginners.
As seen in this article1, stride frequency varies from 150 spm (during light jogging, ~3 m/s), through 180 spm (olympic race pace, ~6 m/s), and goes way up to 230 spm (at 9 m/s). The chart can also be seen in this article by Alex Hutchinson (multiply stride/sec with 120 to get spm):
So target cadence of 180 at all running paces, is a very poor suggestion IMHO. It simply isn't supported by the data. Yes, it might be the most optimal cadence while running 5k in 13 minutes, and yes, there are many people who will tell you that you can jog at 180 spm, but if research is showing that olypmic athletes aren't doing this, then perhaps it isn't the most efficient way to jog after all.
Whether slow jogging at 180 spm can reduce injuries, that's a different story. There are claims around the internet that slower cadences result in "heel striking" and that 180 spm jogging can reduce knee problems, but I wasn't able to find actual research supporting this (and since olympic athletes seem to "ignore this advice", I am not so sure about its merits).
1 Faster top running speeds are achieved with greater ground forces not more rapid leg movements, Weyand et al., Journal of Applied Physiology