Google Gears is a technology that allows you to view and edit your online documents offline, without an active internet connection. As of March 31, Google Docs (an online word processor) is rolling out with Google Gears functionality.
Initially offline access to your documents will be limited to: 1) viewing and searching your document list; 2) viewing and editing word processing documents. Currently presentations and spreadsheets can't be accessed offline as of yet. Also for now, offline access will only available in English.
For more information watch the video below.