Apple Buyer's Guide (model ordered) Apple Buyer's Guide (time ordered)
They keep track of how often Apple's products are released, and how long it has been since their last release. They use this information to recommend whether you should buy now or wait.
Direct link to the section about MacBooks.
As of 1-16-10:
The latest MacBook was released 88 days ago, and is updated every 194 days on average. The latest MacBook Pro was released 222 days ago, and is updated every 200 days on average. The latest MacBook Air was released 222 days ago, and is updated every 255 days on average."
The timeframe varies but usually they renew the Macbook series every two years or so, I believe in January when Apple holds their yearly conference in San Francisco. However, there have been big changes the last two years running, including upgrading all Macbooks to Macbook Pros with more RAM, etc.
