Apple have just announced that the soon-to-be-released iPhone 3G S will include the VoiceOver screen reader, among other accessibility enhancements. Although I'm still uncertain as to the efficiency of a touch screen interface for the blind, this is fantastic news. For the first time, an every day mobile phone/PDA will include a screen reader as part of the core product at no extra cost. Apple's inclusion of VoiceOver into Mac OS X was revolutionary news, and they've now done it again with the iPhone. I'm sometimes rather cynical towards Apple, but I am continually impressed by their commitment to incorporating out-of-the-box accessibility into their products.
It's worth noting that the iPhone is not the first touch screen phone to include accessibility for the blind. A suite of self-voicing applications called Eyes-Free is available for Android which enables blind users to use many functions of the phone. While this is great to see, it's disappointing that this is what I call isolating (or isolationalist) accessibility; i.e. blind users must use a different set of applications to everyone else to access the phone and are thus isolated from the experience of other users. This appears to be a (in my opinion disappointing) trend for some sections of Google, as demonstrated in the separate, so-called "ARIA enhanced" and "accessible" versions of some of their services, wherein they often present a different interface for blind users instead of integrating accessibility right into the existing interface. I think that isolating accessibility certainly has its place - it can sometimes make for a more friendly and easier learnt interface and is the only practical option in some extremely visual scenarios - but in general, I believe it is extremely limiting and inflexible. Admittedly, a touch screen interface is inherently visual and thus presents a new set of challenges. Not only does the user interface need to be spoken or brailled, but the method of input needs significant adaptation to be used by a blind person. This is probably why the Android Eyes-Free developers chose the path they did. However, Apple have taken a better, more generic approach similar to that of most modern operating systems, allowing blind users to use the same applications as everyone else. The new iPhone incorporates accessibility into the core of the operating system and VoiceOver modifies the input method as well as reading the user interface, which allows any application to be accessible with VoiceOver, including all of the in-built applications.
Experience will determine whether Apple's implementation is optimal for blind users. Regardless, they've truly raised the bar for mobile accessibility.
Disclaimer: I have not had any personal experience with either VoiceOver on the iPhone 3G S or Android Eyes-Free. These thoughts are solely based on the information I have gleaned from various internet sources.