Google made a splash earlier today when it reanimated its direct phone sales, selling the Galaxy Nexus directly from the Google Play Store for $399 unlocked. In a Google Groups post, a representative stated that while the hardware is identical to the GSM model that's been available overseas for almost six months, the software gets one important revision: Google Wallet support is added natively. Google Wallet is still only available in the United States.
Google said that the differing software build, "takju", has been posted to the Google Developers website. These AOSP builds are especially handy for modders, who tend to rely on them for backup purposes. The latest Android 4.0.4 build is available for the US "takju" galaxy Nexus, the international "yakju" Galaxy Nexus (both have the identical hardware codenamed "maguro"). Verizon Galaxy Nexus owners who haven't flashed a custom ROM are still waiting around on Android 4.0.2, though a 4.0.4 ROM has been leaked.
And one more thing: the yakju and takju builds are interchangeable on the GSM Galaxy Nexus. You can load either one onto either identical phone and they'll work. So if you imported a GSM Galaxy Nexus months ago and want to get onto the official US release schedule, you can download and flash the takju build to do so. Likewise if you're outside the US and you want to play around with Google Wallet, you can flash the takju build.