Gmail blog reveals that Gmail has been working with IE engineers at Microsoft to fix some of the problems they found with their code and how it works with IE6. In order to see these changes you will need to install the latest updates from Microsoft (or specifically the update described in MS08-022).

The newest version of Gmail pushes modern browser technology to the limit, so initially we weren't able to make it available to those of you who use IE6. Because it was released way back in 2001, IE6 wasn't able to handle the complexity of the new code in a way that met our performance and stability goals. Over the last few months, we've been working with the IE engineers at Microsoft to address these issues: they released a critical update to their JavaScript implementation that fixed a performance problem with how the script engine allocates and frees memory. We also made small simplifications to the UI when it runs in IE6 to improve stability. For example, we removed the drop shadow from contact pop-ups and the rounded corners from chat moles, both of which tended to cause problems in IE6.