A few days ago Sigma announced a couple of lenses: 19/2.8 and 30/2.8.
At first blush I took these as four-thirds lenses, but it looks like Sigma will be making them for both the four-thirds cameras, as well as the NEX. They appear to be fairly small and light, the 19 is the larger of the two and is spec'd at 140g and 45mm long, with a 46mm filter size... not too bad.
I have not searched around for any specs on the 30mm, but it should be smaller and lighter, which would also make it smaller, lighter, and about a half stop faster than the Sony 30/3.5 macro lens, although it will lack macro capability.
These might be the first two interesting options in native NEX mount from a third party manufacturer, pending cost and performance of course.