A short list of points to consider are a sprawling detailed and curated taxonomy, aggressive editorial publishing schedules, community integration, feed generation for partners, topics, venues, articles, various multimedia types (slideshow, interactive, audio, video, audio slideshows...)
I could (but won't) go on. No CMS on the market or from the open-source community meet the very unique set of needs (as well as the ones you can't predict).
I moved elsewhere in the company from the CMS group as this was playing out. Previously we'd used a highly customized version of FatWire's CMS which wasn't sufficient for current and future needs.
Hope that helps clarify things.
(Hi bkudria, sorry I missed you at GoogleIO)