Reading the NDA at your current company in full should be your first step. Beyond that a good rule of thumb is not to discuss in detail anything that your company hasn't already publicly and officially disclosed. Key here is what the company has officially disclosed - not what Gawker, Kotaku or some other site is speculating the company is up to.
I can tell you from experience on multiple occasions that discussing confidential information will not look good in the eyes of a potential employer. In one situation I was working at a game studio and we interviewed someone from a competing studio. The candidate discussed in detail some of the game play mechanics behind their upcoming title. While everything they told had already been published in the various game rumor sites (Kotaku, Games Radar, etc.) our team was still very put off that this person would disclose information that hadn't been publicly announced by his studio. As far as we were concerned if they would discussed info on their current title at that studio they would probably do the same to us, even if it was unintentional.
It is an easy trap to accidentally fall into. Most talented people are very proud of their work and it's human nature to want to discuss your accomplishments when asked. If asked during an interview it's 100% acceptable to politely say "I'm sorry, but the details on that haven't been publicly released and out of respect for my current employer I probably shouldn't go into detail on that." Any company worth working for will respect you more for saying this than answering the question and potentially violating your NDA.