Google Toolbar for Firefox, that now has all the features from the IE version is now out of beta and seemed to be fixed the bugs related to Google Docs & Spreadsheets. The toolbar can open any file from the web or from your computer in Google Docs & Spreadsheets, although the feature is not enabled by default.
Google's online office suite has been localized in 12 languages (French, Italian, German, Spanish, Traditional Chinese, Simplified Chinese, Korean, Turkish, Polish, Dutch, Portuguese (Brazil) and Russian) as Google Blog announces. If the language was a barrier, now Google Docs can be used even if you don't speak English. If it seemed awkward to go to Google Docs and upload files, with the new Firefox toolbar, you can just drag & drop files in your browser.