The same could be said of gitorious.org shutting down, but for the past 8 months it's been inaccessible by the Web or via git. It's just recently returned as a read-only archive (thanks to archive.org, I believe); they claim that clone URLs should work again now, although I've not had reason to try one yet.

Keep in mind that even with announcements and long shutdowns, many projects would be lost without officially-sanctioned archiving; either because their author has moved on, or they might do all of their project interaction via git commands and never see warnings on the Web interface.