Cloud printing is a project that will enable applications on any device to print documents. "This goal is accomplished through the use of a cloud print service. Apps no longer rely on the local operating system (and drivers) to print. Instead, apps (whether they be a native desktop/mobile app or a web app) use Google Cloud Print to submit and manage print jobs." Google says that printers "are treated in much the same way as documents are in Google Docs". Cloud Print will be implemented in Google Chrome and Google Chrome OS, so it will probably launched in the coming weeks.
If you can synchronize your calendar, your contacts or your mail, why not synchronize the documents stored in Google Docs? That's one of the most important missing features from Google Docs. Google already offers some APIs for uploading and downloading files, but they're limited to documents, spreadsheets and presentations if you don't use Google Apps Premier Edition.
Google Docs has applications for editing documents, spreadsheets, presentations and for viewing PDF files, but what about other file types? There's no photo editor, no video editor, no application for editing PDF files or for extracting files from archives. Third party applications could solve some of these issues and make Google Docs even more useful.