My Calendar webpart (OOB) is showing US time irrespective of the customer location, is that expected? if so, how it could be resolved ?
Note: Our servers are in US however customers are in throughout the world.
The My Calendar Web part is most likely going to go off of the settings on the Exchange server.
For SharePoint, the timezone can be set for each application, site and sub-site. It can also be overridden by the user by clicking their username in the upper right of the screen and selecting My Sitings, and then I think My Regional Settings. This will get them the right time for all SharePoint controlled date/times.