I have a 7 year old son and a 5 year old daughter. In the past 2 years I have seen a significant increase in the legos for little girls, but the variety and choices still pales in comparison to that of the boys. Even the 5 year old notices: "where are the rest of the GIRLS legos??? There's SO MANY legos for boys..." However, we have quite a few age appropriate sets for her, and she loves them.
It seems the "girl versions" hit the aisles in the past 2-3 years, and then the legos are growing up with the girls. In other words, as she has aged, the newest releases seem age appropriate for her. However, there are not yet the huge, complex sets (aged 8-12) for her that would be an equal comparison to what we are buying for our son. My hope is that the new releases each year will continue to target these girls as they grow up. We are lucky that she seems to be in the right age range.. if she were a few years older there would be many fewer choices. She is currently doing the "5-12" sets, but really, in complexity, those are more 5-8. Older girls would be bored.
She also has 2 GoldieBlox sets and has to fight off big brother from playing with them. I love the idea behind GoldieBlox and was thrilled that they were selected from over 15,000 submission to get the SuperBowl commercial by intuit.
YouTube full length SuperBowl commercial.