aakk9999 - 1:57 am on Sep 30, 2011 (gmt 0)
What about a 'this widget is no longer available' message? My worry is then that this would thin content and if all yanked pages have this verbiage this would be internal duplicate content?
I presume that these pages have some content at the moment. So adding "This widget is no longer available" should not make all these pages duplicate if there is a sufficient amount of the other content on the page that makes the pages currently differ from each other.
If a widget is gone not to come back I would then do as g1smd says, that is either serve 410 or 301, depending if there is a good page to redirect or not.
If a widget is temporarily/currently not available, I would leave the page returning 200, and add the message to the page alongside the lines:
"This widget is not currently available. Why not try nnn mmm instead?" (where nnn mmm would be links to similar widgets).