This is going to backfire on Google in a big way if it's not a robust solution. Beyond-the-basics off-line support is a subtle but very complex challenge.
Google hopes other companies will use Gears to extend their own software and services. Some Microsoft rivals, including Adobe and Mozilla, which is behind the Firefox Web browser, are collaborating with Google on the technology.
But it could also help Google’s rivals. If the Gears technology proves effective, scores of software programs, including Yahoo Mail and Microsoft’s Hotmail, might one day be used offline to read e-mail messages and to compose new ones. The new e-mail messages would be sent the next time a user connects to the Internet.
Google said Gears was in early stages of development. “This is not a solution that is going to work with everything on Day 1,” Mr. Smith said.