I have an iPhone 4 and I have just noticed that when I am not in an app, there is a large Q in the top left hand corner. It is right at the top anyone any idea what it is

I've no idea what it means but it happened on mine too. I restarted the handset and it was gone.

Yeah, it's disappeared now. Very strange.

It could be related to Quicktime.

It wasn't the same Q as the one on QuickTime. I took a screenshot on my phone but I've no idea how to upload it from my phone.

you are not alone, the plot thickens