the new york times has had something similar to this for years.

you can highlight words and it will show a "question box" that you can click to see more information about the word, google search, etc. it's displayed inline so you don't need to navigate away.

it's a nice idea, but it's terribly annoying.

sadly not. I had it running on my own blog for a few weeks, collecting data which I then analysed. I'd have loved to have got a nice plugin put together for it all but I didn't get it that far.

Got a distinction for it though! You can read a little about it here: http://www.puremango.co.uk/2009/06/adaptive-web-sites/