"google can disregard nofollow on a case by case basis"

This is somewhat correct. While Google won't disregard noindex/nofollow directives (or robots.txt Disallow) it can - and will - show "blocked" pages in SERP if the quarry is specific enough or a the page is "strong" (lots of inbound links/strong social signals and etc...)

However, it will not show in page info (hide description and title) and use alternatives sources of information to fill those out instead.

For example: it can use DMoZ info instead of the real one.

Source: http://www.incapsula.com/the-incapsula-blog/item/395-new-sni...