Love them or hate them, cell phones are ubiquitous. Although it seems as if everybody has them here in the U.S. (and persists in using them while driving), it's still a much smaller percentage of the population than occurs elsewhere. Japan, for example, land of early adopters and gadget lovers. So what has this to do with sensors? Well, let's look at two types of sensors being integrated into cell phones.
From a recent story online at MobileMag, we learn of plans to use a facial recognition sensor to allow users of Japan's Vodafone K.K. subscribers to skip the annoying entering of passwords. This feature is slated to become standard with later versions of the 3G phone. This is interesting for a couple of reasons: first because it's another example of the integration of biometric sensors into various consumer products and second because of the emphasis on phone security. We are not, as far as I know, anywhere near as security conscious with respect to our phones as we probably should be (for an interesting discussion, read this and make sure you read through the comments.)
So, on the one hand you have enthusiastic add-a-sensor talk. On the other hand you have this comment from Bourne Research about hurdles to MEMS sensor integration into cell phones. Namely, that cell phone manufacturers may want to add MEMS sensors to phones but don't want to have to write the drivers necessary. Why? Because the handset manufacturers aren't convinced that the features made possible by adding these particular sensors to the phones are worth the time and expense of creating the drivers.
Is the difference in enthusiasm based on how the sensors are used? One feature, the facial recognition sensor, presents a clear benefita significantly easier way to secure your phone rather than having to enter (and remember) long passwords. The MEMS sensors, on the other hand, can create an easier-to-use interface, relying on tilting the phone to scroll or move, rather than using the keys. While consumers are interested in security, a better user interface may be a lower priority for them, and by extension, the handset manufacturers.