First of all this is a great product. We have been using TeamCity for years. We switched from Cruise Control and never looked back.
After doing simple CI for years, we are now slowly moving in the direction of a "deployment pipeline".
Thanks in part to books like this: http://www.informit.com/articles/article.aspx?p=1621865
I know that the goal of a deployment pipeline can be achieved with TeamCity by connecting builds together and so forth, but it is not as iniuitive as I would like.
I also know that there is a plugin or two, but it seems that some native support could be added to help create and visualize a "Deployment Pipeline".
Though I have never used GO, it seems it addresses this concept.
This screen shot from a hudson plugin seems to sum it up..
So in summary, I wanted to find out if the TeamCity Team could shed some light on this topic.