Funny, I was wondering about this exact thing yesterday. Trying Google though (hadn't thought about other DNS providers), the traceroute went to somewhere within Europe or maybe even Amsterdam. Being from the Netherlands, that'd be very close, there just is no way 13ms is a ping from America.
So I guess 8.8.8.8 is multihomed or however they call it. Still, the geoIP databases claim it to be in Mountain View where Google is, so I wasn't not sure exactly how this affected 'split horizon' (on which, as far as I know, the DNS decides which IP(s) to return for the requested hostname).
According to the compute engine talks from this year's google IO, they have their own private network covering most of the world and uses anycast for external Internet Addresses. This basically means that a connection from you will be routed to the nearest google data center, and from there to the final server using google's private network.
Google DNS uses both anycast and multihoming, so you will both be routed to the nearest google data center and then to the closest DNS server inside google's private network.
To be precise, HonestDNS uses Anycast routing to situate the same IP at multiple places around the globe, letting BGP and least cost path routing send users to their best location. The DNS protocol works particularly well for this.
So I guess 8.8.8.8 is multihomed or however they call it. Still, the geoIP databases claim it to be in Mountain View where Google is, so I wasn't not sure exactly how this affected 'split horizon' (on which, as far as I know, the DNS decides which IP(s) to return for the requested hostname).