Google is now dropping IE 6 support for most of it's products, starting from YouTube, Google Docs, and more will follow. The official post is here and IMHO, it's a good decision, not based on the war between those two companies. Maintaining a lot of browser in one application does have a drawbacks, since it may requires a lot of hacks to work in every browser available and IE 6 (and below) is surely one of those product that need a lot of hacks.
I believe other companies should do the same with Google and drop support for IE 6, since Microsoft has launched IE 8 for some time and i think it has improved so much on the security and also the technology supported by the products.
On my course (Internet Application Engineering), i only asked my students to create an application which SHOULD work with IE 8 and Firefox 3.5+. I will give them bonus points if they are able to make it work on other browser as well (Chrome, Safari, Opera, IE 7). I think i made the correct decision on this and it has been decided since few months ago.