The Galaxy Nexus has been Google's most popular Nexus device so far (and hopefully the Nexus 7 will be even more popular). Google dropped the price of the Galaxy Nexus to $399 a few months ago from something like $700, which was the retail price at most US carriers. That made the Galaxy Nexus a very interesting choice for people who want to escape the carriers and 2 year contracts, and their costly monthly plans.
Google now is moving a step further to complete liberation from carriers with another $50 discount for the Galaxy Nexus, now making its price only $349. That's dangerously close to the Galaxy Nexu's original price of $299 on contract on Verizon, when it launched, but you get to get a pretty expensive 2 year contract with that. If Google manages to push more devices like these like the Galaxy Nexus and the Nexus 7 in the market, the carriers should have less and less control over our devices.
Also with the Nexus program, Google could increasingly control a larger number of devices in the market, that they could update themselves, instead of the manufacturers, so they could shoot 2 birds with one stone. There are at least 5 new Nexus devices rumored from each of the top 5 Android manufacturers for this fall, and they all should arrive with Android 5.0. It will be interesting to see if those devices will also be sold through Play Store, independent of the carriers, although I'm sure there will be versions of them being sold through carriers as well.
Until then you can get the Galaxy Nexus for this low $349 price from the Play Store. The phone is compatible with both AT&T and T-mobile in US, as well as 200 other GSM carriers all over the world. You should be receiving the Android 4.1 update by mid-July, as well.