Thunderbird 3.0b2+ (F11, x86_64): Opening a sent mail I see only "You" as sender. This isn't very helpful for people having multiple personalities, err, identities. One has to hover over that "You" to see the actual sender, which is more than user-friendly.
We filed this bug in the upstream database (https://bugzilla.mozilla.org/show_bug.cgi?id=498977) and believe that it is more appropriate to let it be resolved upstream. We will continue to track the issue in the centralized upstream bug tracker, and will review any bug fixes that become available for consideration in future updates. Thank you for the bug report.