So it seems the recent departure of top technical people has not helped Twitter's stability (maybe all that money will?). The site is totally unavailable at this time (645 edt) and has been for at least 1/2 hour. Better than sort of working I guess?
Strangely enough the server that is www.twitter.com is pingable (I would have thought that would not be possible at any time --makes them very DOS vulerable).