Updated: Kenko announced 10mm and 16mm extension tubes that support communication between camera and lens for both the m4/3 and NEX mounts, providing a macro capability for pretty much any lens. US costs haven't been announced, but in Europe the price is expected to be just a bit over 200 Euros for each tube.
Because the extension tubes have full electronic connections in them, focus and exposure should work normally. Since there are no additional optical elements involved, the properties of the lens being used should remain the same, too.
The 10mm tube is 48g (both mounts), while the 16mm tube is 70g (m4/3) or 75g (NEX). This makes for a small, light, convenient macro option for travelers and gives you 10mm, 16mm, or 26mm (combined) focus extensions.
The tubes will be released to the public in April.