Are you sure you were eating enough? Eating more is almost always the answer to plateaus. Also squats are the best exercise for all-around strength, not just legs. Squatting more weight does wonders for other things like bench and overhead press.
I could have eaten even more though. But I don't get the whole eat until your stuffed mantra either. It seems so unnatural and unhealthy.
I also plateaued on Squats during SS after about 4 months, so I lowered my work weight to 80% during my middle squat day (Wednesday in a MWF routine), as Rippetoe suggests, and I immediately broke out of it.
Anyway, I just discovered HIIT training, which has made a world of difference. I'm actually gaining strength and mass every time I work out, and I'm eating less now than I did on SS.
SS works for some people, but I think it depends on your genetics. Or maybe your right and I'm not eating enough. However, my system just can't handle that much food without GI problems. Also, I was getting a big fat belly along with it.
HIIT training has been working for me and after 2 months the gains are still there and better than those I was getting on SS. There also is more evidence that it works than SS has, I believe. Like I posted on another thread, checkout the boise experiment: http://boiseexperiment.com/HeavyDuty/?page_id=308
Anyway, each to his own.