I don't think Friday was a doji, but they generally are a indicator of a change in direction, some are more stronger than others.
Looks like a doji to me, but I think dojis represent indecision; neither the bulls nor the bears had control. It could reverse or it could not. It's possible that a doji forming after certain other patters mean different things, but I haven't studied candlechart formations in a while. Investopedia says: Here you can learn about different types of dojis: http://www.streetauthority.com/terms/doji.asp This page talks about some doji formations and what they may or may not mean: http://stockcharts.com/school/doku.php?id=chart_school:chart_analysis:introduction_to_candlesticks