Liquidity is a measure of how easy it is to turn an asset in to cash. For example, property is not very liquid at all. It could take several months to sell a house. Stocks which are heavily traded are more liquid than a penny stock only you are interested in.

As for CMG? I think blustar said it pretty well already:
http://boards.fool.com/Message.asp?mid=25129748&sort=whole

Did that help?

- Rafe