Android: Despite being otherwise entirely hooked into the Googleverse, your Android phone can't edit Google Docs files on its own. The handy GDocs app steps in to download and edit (some) docs, upload files from your phone, and view PDFs.
It's not an elegant cloud solution to your Android system's lack of Docs connectivity, but GDocs gets the job done. Set it up with your Google credentials, and the app grabs your Google Docs folder and file list. Press and hold on any file to edit its title, delete it or download it to your SD card. If it's a word processing document, you can download the file, edit it through GDocs (or another word processing app you might have), then re-upload it to Docs. Not exactly an automatic, save-as-you-type setup, but then again, you probably wouldn't use your phone for more than just quick, minor edits.
If you need to view a PDF file from your account, GDocs can do that natively, and with Docs now allowing any type of file upload, you can use GDocs to push files off your phone to your Docs account.
GDocs is a free download for Android systems. If you're having trouble connecting to your account and listing files after GDocs updates, be sure to visit the "Accounts" section, under the "More" options, and hit "OK" to re-verify your credentials (and hopefully that wonky bit gets fixed).
GDocs for Android [Google Sites]