The spell checking feature in Google Docs and Presentations now uses the power of Google search. The major benefits of this are:

– Suggestions are contextual
– Contextual suggestions are made even if the misspelled word is in the dictionary
– Suggestions constantly evolve

The new spell checker is available for English documents and presentations, but we plan to bring it to more languages soon.

Languages included:
English only

For more information:
http://googledocs.blogspot.com/2012/03/spell-checking-powered-by-web.html