Good news, there is none! Sort of. Bioware's got their mouth so shut, since like I said, E3 is nigh. I actually dug up this tweet that's been causing a buzz. It's a picture of the mocap set! That's all it is!
Apparently there was some sort of survey about Mass Effect 4? Honestly, I remember taking a survey, I'm wondering if I'm thinking of the same one. People have derived some plot details, you can go look at the Internet's wild guesswork here.
... I think the new rumored plot looks badass. I was scared to death ME4 was going to be open world and plotless. How in the fuck was I going to MSPaint that?
This article gives a few more plot details, and discusses the idea of seeing old trilogy characters. My guess is that Liara, Garrus and the rest of the crew won't come up any more than maybe an easter egg or two. ("Oh man, did you all ever hear about this old bastard named Archangel?" That sort of thing.)
... I'm still looking for a YouTube video of that Citadel audio I promised. If you know where it is, point me to it!