Click the "Write" line.
Enter a Title.
Enter some text in the body.
This is a new post so the Properties->Issue Date is set to "Update to NOW".

The (actual) time now is 13:30 on 3 Aug 2011 and the "Set to:" box reads "08/03/11 13:30". Clicking in the "Set to" box opens the jQuery calendar pane which displays the correct date of 3 Aug 2011.

When I click "Preview" the preview post displays the date as "March 8th".
If I publish the date is set correctly to "August 3rd".

This behaviour is also exhibited when editing a post.