wood s lot also points to the new experimental Google toys, among them:

• Google glossary: Find definitions for words, phrases and acronyms. Can Dictophane be far behind? (Actually I'd like to try a quick implementation -- I've got the tools in place with Quick Doc Review -- and propose it to a dictionary site).
• Keyboard shortcuts: Navigate search results without using your mouse. This is pointing towards what I'd hope for if Google were to allow navigation of discussion threads: "[using a search engine] I find a message in a thread. I should be able to follow the thread up and down its hierarchy (at the search site)".