Wired reports that proper Nano computers are very close indeed -
" But do we really need to develop technology so powerful that it can cram all present-day computer power into a space no larger than a sugar cube?
Merkle seems to think so. "Every time people say 'Gosh, what do we need more computer power for?' somebody comes up with a new application. Just take a look at Windows: we're going to need these molecular computers to run Windows 2015." Yes indeed.