I noticed this while writing an e-mail in Outlook 2007.
When I insert a special character (using UniChars) after some text, a space is inserted before the character.
As soon as I copy some text to my clipboard, the problem is solved.
I only observed it in Outlook 2007. I also tested it in Notepad, Notepad++, Delphi 7, Word 2007 and OO Writer 3.2, but it seems to work correctly in those apps.