Google Takeout is a service that makes it easy to export your data from various Google services. It’s proof that Google has a different philosophy than some other services (e.g. Facebook) that put up roadblocks when you try to leave with your data.
Takeout makes it easy to download information from Google Voice, Plus One, Buzz, Picasa, etc. in a zip package that can be stashed away in ase you ever need it.
Note that Facebook also now lets you download most of your data in a zip package, probably thanks to competitive pressure from companies like Google.