Microsoft has started distributing Windows Phone 7.5 to the Samsung Focus 1.4 for AT&T, which marks the near-completion of its update rollout. The only outstanding handsets left are Dell's trouble-plagued Venue Pro in the US and the Samsung Omnia 7 on Telefonica in Spain, the latter of which is currently being scheduled for its software overhaul. The 7.5 OS update got off to a rolling start on September 27th and now, a month and a half later, is being delivered to the vast majority of Windows Phones.
At first blush, that may not seem like the fastest execution in the world, but when you consider the multiplicity of phone makers, carriers, networks, and regulators that an update like this has to appease, it's actually a remarkably quick turnaround. Just take a look at the scattershot fashion in which Android upgrades make their way around the world for a salient comparison.