It’s pretty cool functionality inside of eclipse. It keeps you from having to google your way through blog posts. 😀
Install it the same way that you would any eclipse plugin.
Here is Adobe’s explanation of it.
With Blueprint, Flex and Flash developers can now query for sample code just as easily as they use auto-complete. Blueprint brings the power of the entire Web inside of the Flex Builder 3 Development environment and provides sample-centered search results that allow the user to quickly look through many different examples from many different websites including documentation, blogs, and forums.
The Blueprint preview is prerelease software that is not supported by Adobe and may contain bugs. We welcome your feedback, so please use the feedback link below to request features, make comments and report problems. Please also note that this is a research project and there is no assurance that there will be a shipping version of Blueprint.