A user complained about the GMT offset not being applied to meetings received from other time zones in Outlook 2010:
"Having an issue with Outlook 2010 where the GMT offset is not being applied to meetings received from time zones other than local. Meetings appear ok on mobile email and webmail calendar as well as Outlook 2007 on the same operating system. As soon as Outlook 2010 is installed meeting shows up at the wrong time."
After suggesting he turn off all devices syncing with the calendar, he discovered the problem:
Meetings sent from Outlook 2007 on Exchange 2003 and received by Outlook 2010 on Exchange 2007 that are accepted on the mobile device, where the time zone is automatically set by the network, appeared without the GMT offset in Outlook 2010 on the recipient's side. After manually setting the time zone on the smartphone, the appointments appear at the correct time in Outlook 2010.
Strangely enough, anything sent from Outlook 2010 on Exchange 2007 and accepted by the same smartphone appear ok in the recipient Outlook 2010.
Moral of the story: It's always the time zone setting. :) While this is true with all versions of Outlook, it's especially true with Outlook 2010 as it handles time zones differently, due in part to it's ability to "float" all day events.
When Outlook 2010 is installed on Windows 7, you must use the proper time zone for your location. If your area does not observe DST, do not use a time zone that does, then disable the automatically update check box.
Troubleshooting Tip: When you sync a smartphone with the mailbox and something isn't working as expected turn off the phone. If the issue goes away, the problem is not with Outlook. If it doesn't go away, identifying the cause will be easier when outside forces aren't in the picture.
A script to troubleshoot issues with Exchange ActiveSync (TechNet blog)