Google's latest feature addition brings a classic and sorely missed feature to Google Docs.
Pagination is one of those things most people take for granted in your desktop word processor program. It's the "view" in Microsoft Word that I use the most, since it gives me an idea of how the page is going to lay out when printed. It's one of the biggest reasons I haven't used Google Docs for more of my word processing.
Functional pagination requires a lot of technology behind it, and oddly enough the necessary CSS wasn't introduced until CSS3. The CSS3 module, dubbed "Paged Media", includes all the necessary items and builds upon the concept of "print" style sheets.
To quote the CSS3 specification doc: "It (Paged Media) builds on the Box model module and introduces and defines the page model and paged media. It adds functionality for pagination, page margins, page size and orientation, headers and footers, widows and orphans, and image orientation. Finally it extends generated content to enable page numbering and running headers / footers.".
Since it's a CSS3-only module, only Google Chrome and the latest version of Opera support the CSS3 components of the Paged Media module. Firefox has support for paged media in core but is unclear whether the patch to support it made it into FF4's release. So for now, Google Chrome is unsurpringly your best bet to play around with page breaks in Google Docs. Read about the full release on Google's blog.