Today I stumbled on the weirdest bug. It seems that the equals operator (==) is not symmetric in IE8.
Meaning that sometimes, even though a == b yields true, b == a will yield false.
I discovered one such scenario when working on my project Packages JS.
Have a look at my test page. Does your browser handle it correctly?
Please leave a comment here with Browser and OS version and test result. I am curious about other browsers and versions.
Stijn de Witt 
I had a friend test on IE9 RC (on Windows 7) and it turns out this issue is fixed there.
Just tested in IE6 and the bug is present there as well. I have not tested in IE7, but seeing as it’s present in both IE6 and IE8 it’s a safe bet that it’s also in IE7.
I can confirm: This is also broken in IE7.
Correct in FF4.0