A lot of corporations use Akamai, Microsoft included -- http://www.akamai.com/html/customers/customer_list.html.
Interesting enough, the only name missing from that list? Google.
I guess there could be some issues since this makes Google's competitors in other markets reliant on them, but from a "too much good infrastructure in one company" standpoint, I don't see how there would be anti-trust concerns.
Why would they want to make other sites on the web faster?
They rely very heavily on web, and it's absolutely important for them to speed up web for people to keep moving away from native.