Major player wants to partner with Microsoft to take Google down a peg

Microsoft Program Manager Ian McAllister wrote about an intriguing meeting he attended "with some senior players at another Tier 1 internet company". The other company's representatives offered to "work together" with Microsoft, in order to prevent Google from dominating the Search and/or advertising business. Here's the whole post:

"I had a meeting the other day with some senior players at another Tier 1 internet company. I won't share the name of the company, but suffice it to say that I'm 99% positive you're a customer. At the end of the discussion one of the people I was meeting with threw out a blanket offer to brainstorm other ways in which our companies might work together. He then stated that his company was willing to entertain ideas for working with Microsoft that would help our Search and/or advertising business, with one of the goals being to prevent Google from dominating those spaces even more than they are now. He was essentially saying that his company would help Microsoft level the playing field with Google in search and advertising.

I'm not sure if this offer will develop into anything or implying that I'm a person who could capitalize on it, but I do find it extremely interesting that Microsoft is on a different side of this triangle than we would have been 10 years ago."
(emphasis mine)

I've met Ian before and he's a great guy. I too find it interesting how Google has become the most feared Internet company, a position Microsoft was in 10 years ago. Hmmm, I wonder who the "Tier 1" Internet company is? Yahoo? IMHO they're the only other bigco apart from Microsoft and Google that has a 99% chance of having you as a customer. Who else could it be?