I was homeschooled all the way through. I started college when I was 14 and managed to graduate without any problem. When people are amazed at how young I was when I started, I just point out that the main issue with a larger class is that the teacher has to go as slow as the slowest student in class. So, since I was able to go at my own pace, I was able to cover more ground more quickly.
One benefit of homeschooling, at least in my situation, that I think is often overlooked is how closely it mirrors college study habits. I was expected to do a lot of my own coursework and homework in high school. This dovetailed very nicely into the expectations my professors had in college. From that standpoint, I think I was better equipped than many of my classmates.
We (my brother and sister were also homeschooled) had a licensed teacher administer state placement exams every year to ensure that we were at least at our expected age/grade level. We were also part of a local group of homeschoolers, which let us do the normal field trip / science fair / social stuff.
Even while I was in school, things definately went from the fringe to mainstream. In fact, the main reason for the administered tests at first was to ensure we were better covered if the state (Nevada) elected to take legal action.
The other obstacle that I faced, which may be less of an issue now, is that I needed financial aid when I went to college. My dad and I had to closely with the registrar to get them to actually change admittance criteria. In the end, they still needed a high school diploma and transcript, but they decided that it was ok for us to just produce both of those documents.