Anyone who regularly visits 'Galaxy Nexus' forums has certainly seen this comment multiple times when complaining about the lack of updates from Google on this "Nexus" phone. Well, there are two points those people are missing, and they are usually quickly addressed by the more savvy GN users.
1. This phone received an update within seconds of being unboxed.
2. Faster doesn't mean more often. It means faster than non-Nexus devices. Now, it will be a little different for the GSM Nexus and the Verizon LTE Nexus, but for the most part these updates will be much sooner than updates for every other phone by every other manufacture. Because the GN is a 'vanilla' version of Ice Cream Sandwich, we don't have to sit around and wait for the manufacturer to apply their custom skins and bloatware. That is a process that often takes months. Look at the Droid Razr, it still has no ICS update and ICS has been released since the end of 2011.
Also, it is assumed that Google had some issues with the 4.0.3 version of ICS when they tried their test rollout on the Nexus S - which caused them to not roll it out en masse and head back to the drawing board. I think that is why we are now rumored to be getting a more advanced/tuned 4.0.5.
So, be patient. 4.0.5 is on its way in the next few weeks.