Does anyone know where I can find SoundBridge software version 3.0.52. All referance links go either to the M1001 page or to a 505 error.

Links are broken. What version do you have currently? The latest non-beta is 3.0.44 and is good for just about everything.

3.0.52 fixed some issues related to the BBC services but those fixes are not now required.

What product are you trying to update?

Les.

There seems to be no way to find this firmware anywhere on the web!

Could someone with a downloaded copy post it online somewhere? Would that be permitted by Roku, if they aren't willing to provide a link themselves?

As Les said above, it is no longer available and is not required. 3.0.44 is where the Soundbridge development ends.