Superman might be getting handled a bit better now than he was in some properties, but in terms of overall exposure I don't think he's been playing second fiddle to Batman. Has the massive adulation for the Nolan films (cementing Batman's 'iconic' status in public consciousness) skewered people's perspectives a little?
Since 1978, we've had:
6 Superman films
7 Batman films
Hardly a massive difference. Superman has also had more TV properties (in the form of Superboy, Lois & Clark, and Smallville) since the 1970s. Batman only really had the 60s TV Series and then Gotham, which isn't even Bruce Wayne/Batman-centric.
In fact, if you look at the chronology of things, Superman has had some form of TV show or film (charting various stages of his life) pretty regularly since Christopher Reeve first pulled on the cape
Superman I - 1978
Superman II - 1980
Superman III - 1983
Superman IV - 1987
Superboy TV series - 1988/1992
Lois & Clark - 1993/1997
Smallville - 2001/2011
Superman Returns - 2006
Man of Steel - 2013
No matter whether you like these individual properties or not, they all helped keep Superman in the public eye as a character. I'm not even taking into account the comics or various animated series. The films and TV shows are the main ones which will find a general mass audience amongst those who aren't even Superman/Batman fans.
This notion that Superman is a little hard done by is a fallacy IMO. Batman is simply seen as a 'cooler' character by many because of his methods and somewhat anti-heroic approach as opposed to Superman's very straight up character. It doesn't mean that he's been promoted much more by the studios. And that's not me having a go at Superman by the way; despite my avatar, Superman is and will continue to be my #1 favourite superhero character of all time.