I didn't remember hearing about those; you say that like it's Bad, well, dark innuendo at least, beerlord.
A lil while googling about them seemed to say no-one's sure what good or bad effects they have, if any. And they're in a lot of things:
"According to one study...foods with the highest relative phytoestrogen content were nuts and oilseeds, followed by soy products, cereals and breads, legumes, meat products, ...vegetables, fruits, alcoholic, and nonalcoholic beverages."
And well, Japan has the world's greatest life expectancy doesn't it? And they have soy everything.