Source code for Android 4.0.4 (AOSP tag android-4.0.4_r1.1), the latest incremental update with "a few hundred changes over 4.0.3," is being pushed to AOSP (Android Open Source Project) as we speak by JBQ, one of AOSP's main sourcerers (yes, I just made that word up).
This is excellent news for any ROM developers compiling their ROMs from AOSP (such as CyanogenMod) - chances are 4.0.4-based ROMs will start appearing very soon, maybe even tonight. Oh, and, of course, it's even more excellent news for custom ROM users (raise you hands).
Earlier today, official 4.0.4 updates got pushed out to the Motorola XOOM Wi-Fi and the GSM Nexus S. Hopefully, we'll be seeing a lot more of these official updates in the coming days - JBQ has only given us the standard disclaimer:
I do not know the schedule for deployment to consumer devices, especially in situations that involve additional per-operator customizations done by the device manufacturers and/or in situations that require operator approval prior to deployment.
Update: The binaries are now up for the Nexus S (crespo), XOOM Wi-Fi (wingray), and Galaxy Nexus (maguro). These are useful for developers - if you're an end user, you probably won't care about them as much.
Source: Android Building