You need to understand what OpenCL (and GPU computing in general) is good for, and what CPUs are good for, to understand why it hasn't been implemented a lot more (and also why it's not necessarily faster).
GPUs are very good at one thing: performing long calculations on large arrays of data. That is, processing video, scientific data, etc. On a consumer-level laptop or desktop GPU with well-optimised code your speedup is typically less than an order of magnitude. Often you'll find your CPU is actually faster and that you need a Tesla card to see real benefits.
There is a significant bottleneck in transferring data between your main RAM memory and the GPU's memory - the data needs to be transferred to the GPU, operated on, then transferred back. This is why your typical applications such as email, iTunes (and so on) do not use the GPU. They don't operate on large arrays of data and so if you did try to use the GPU, you would actually slow things down.
Basically, OpenCL and CUDA are nice. Just don't fall for Apple's marketing speak, instead try to understand what the technologies actually do and you'll realise that most people won't see any significant benefit for a few years yet.