Heads up, all you My Phone users out there. The service will be offline starting at 8 a.m. EDT Monday through sometime Tuesday morning while Microsoft upgrades the service.

From the My Phone blog:

On October 5th, 2009 at 5AM (Pacific Daylight Time) (check your local time here) the Microsoft My Phone service will be unavailable while we upgrade the service. The service will come back online on October 6th, 2009 Tuesday morning PDT. Stay tuned for more information. You can also follow us on http://twitter.com/msmyphone for updates.

We're expecting My Phone to play a big part in the Oct. 6 Super Duper Windows Mobile 6.5 launch day events, so an upgrade outage is not expected. Stay tuned, folks.