The Nexus One should eventually have at least two docks, a Home Dock and Car Dock.  We already know the phone comes with a few contacts on the bottom from this image engadget has of their on hands review. And we also saw some reports of docks getting past the FCC with bluetooth included.  There is even more evidence of the docks in the user manual as well.Specifically, in the Car Home section of the manual it mentions the use of the car dock:

Car Home is designed to work with the optional Nexus One car dock accessory (coming soon), though you don’t have to own a dock to use it.

And, in the Clock section of the manual it mentions the use of the home dock:

Clock is designed to work with the optional Nexus One desktop dock accessory (coming soon), though you don’t need a dock to use Clock.

Finally, there is one more mention of the docks in the Sound & Display Setting page of the maunal:

Dock audio

Available when the phone is inserted in a Nexus One car dock or desktop dock. For a car dock, opens a dialog where you can set whether music and other media audio play through the dock speaker and whether to use the dock as a speakerphone. For a desktop dock, opens a dialog where you can set whether music and other audio play via the audio line out port. Your settings apply only to the dock you are using; you can have different settings for different docks.

So, the car dock has a built in speaker…and possibly a built in microphone.

Nexus One Manual

Related posts:

1. Nexus One Desktop Dock Now Available
2. Moto Droid Docks are $30
3. Nexus One Car Dock – Photo

Car Dock, Google, Home Dock, N1, Nexus One Docks