OK, 'search' is working fine now but there was still a problem with 'New Posts'.
I normally access SU via a bookmark to:
but it's not been working since the recent downtime.
For reasons best known to myself I'm using an old version of Firefox, v26 to be precise.
When I go to 'New Posts' I get "We're still working hard to fine-tune the server. Please wait, we'll be back ASAP." and a cartoon of a man frantically typing at a PC. He's probably sending me the lecture about always running the latest browser version.
Anyway my solution was to change the bookmark to: