It's only a first step initially, but the expansion of Google Cloud Printing to mobile devices could be a sign of things to come.Writing about it on the Google Mobile Blog, the company says that beta versions of Google Cloud Print for mobile documents and Gmail for mobile are being rolled out over the next few days. In an ideal world, this means you can find a document on your smartphone, which you can select for printing, finding that very document waiting for you when you arrive. Yes, just select 'print' from the dropdown menu or click the print link next to other types of documents, like PDFs for example, Google will sort out the rest.Well, sort of. You'll need to set up your printer to 'talk' to Google Print first. That step requires a Windows PC. Not a Mac, nor a Linux machine, but a Windows PC. You will also need a phone that supports HTML5, such as devices running Android 2.1+ and iOS 3+. Finally, you'll need to be using one of the Google apps to access the menus.All of that makes it a little more niche than we would like, but as we said, it's a beta and a significant first step. Over time, we suspect it will be a useful tool, especially when Linux and Mac support is added. That's apparently coming 'soon'.