Ah, sorry. In the latest firmware, you can enable a "peaking" highlight of in-focus edges. So, for manual lenses (like the Nikon 24mm I use) I don't have to rely on the focus assist magnification to ensure i've got the focus right. As I adjust the focus, the NEX highlights the in-focus edges with a White (or red/yellow) border.
It's very useful when the subject is moving and focus assist isn't much use. I'm sure there was a YouTube video but I might make my own tonight