O.k folks, it looks to have just been a temporary blip for one of our service providers, it only had a small impact on our performance and lasted for about 5 minutes.
Things have been calm for the last 20 minutes or so now, so I don't anticipate it developing into anything more serious.
As always, thanks for being patient.
Our monitoring is currently saying that the management app is running a little slower than it normally would, although it still appears to be usable.
Status pages and message delivery don't appear to be affected.
We're going to take a closer look, and I'll be in touch as soon as we have any more information.