[Note: This deal could stop working at anytime. But it was working as of June 10, 2009 2:50 PM]
Well, I would say this is quasi ironic.
Check out the results of the top of this link: http://www.bing.com/search?q=att
Notice how it has a "Bing Cashback" logo at the very top result which is the AT&T Official Wireless Site.
So apparently, if you use Microsoft Bing to buy a phone at AT&T, including the Apple iPhone 3GS, you will get 35% off your purchase!
Microsoft and Apple are "partners" here. Like I said, quasi-ironic.
There is a noted stipulation that this is for new subscribers; that could be true, but I can't verify it.
Check out these links for more info on this:
And as always, your mileage may vary (YMMV) :-)