This bug affects:
You should see green message above which means that cookie was invalidated by setting it with past date.
What actually happens:
Green message when opening this page standard way (typing address, following link from other page), and red message when opening this page from newsfeed, mail etc.
Go to Site Preferences, change some irrelevant setting and hit ok.
Cookies are disabled for this domain when opening this page from newsfeed. And I mean no cookie support at all! ZERO! (GMail will throw 'Cookies Disabled' error when trying to open mail from atom feed).
This is a bit different issue to the one above, contrary to what you might thinkCookie test:
This was also first reported by me as a widget bug:
#213362 | Site Preferences blocks incoming cookies - testcase widget