This is sad. I thought she pla*** her part in the Columbo episode very well. Being friends with Peter Falk may have helped her performance as she was very natural and delivered on several levels, finding complexity with a supporting role; signs of a good actor.
Sad news indeed. RIP Gena Rowlands. It's a shame she wasn't in more films or shows, or at least not ones I've seen. There was a Circuit Bulletin article (random tech news site) about her son (or grandson?) that was interesting but I can't find it now.