The research you're referring to is that of Dr. Irene Pepperberg. Her research, which is often met with skepticism, is exquisitely thorough and her conclusions are completely sound. I had an opportunity to meet her about 10-15 years ago, while I was in grad school, and I have to say that I was blown away. It's wonderful stuff. Here are some links about Dr. Pepperberg and her work.
http://www.edge.org/3rd_culture/pepperberg03/pepperberg_index.html
http://www.alexfoundation.org/

And here's a brief review of her recent book:
http://www.2think.org/parrots.shtml