Get latest posting: In the main page http://mathoverflow.net and also when viewing questions under http://mathoverflow.net/questionshttps://mathoverflow.net/questions sorted by 'active' (yet not for the other ways of sorting there) every question has a line of the form
"35m ago Unknown 1"
which shows the time and the author of the latest answer or edit. If you click on the time component - here "35m ago" - you are directed to that posting.
This also applies to and can be useful on this "meta".