It's not clear if this price requires Google to pay a subsidy to Samsung, the maker of the Galaxy Nexus. Either Google has a deal to get them at wholesale price and eat any margin or it will pay Samsung some subsidy and take the loss.
It's clear Google is trying to get back on top of the retail game, probably to help promote both Android and the Google Play venture. Play is the rebranded Android Market that Google is pushing as the unified retail outlet for Android content, and now phones.
This raises an interesting thought -- will Google continue this phone selling venture with Motorola handsets once the merger between the two is complete? Imagine being able to buy any unlocked Motorola smartphone direct from Google at a price similar to that of the Galaxy Nexus.
Google maintains it will keep Motorola's operations separate from its own, and this would be one way to do that while still participating in product sales. Samsung is separate from Google's operation, yet it's now selling the Galaxy Nexus directly. It could certainly do that with Motorola phones and claim separation to appease other Android partners.
This is pure speculation, nothing either Motorola Mobility nor Google has said would indicate this might happen. It sure would be an interesting thing to watch unfold if it did.