Blender developers have decided to keep on the old track, cpu rendering instead of using much faster gpu. Reasons for that have been quite obvious as they wanted blender to be as multi platform system as possible. There are numbers of graphics cards and it would be unwise to make blender capable of rendering using their gpus. Why? Well, we want our developers to do something else than that, and not just that.
However, in professional 3d use when there is a technological breakthrough, it is time to move on. No one wants to leave business just because their tools are getting too old and uncompetitive.
The good news is that there is no need to make hard decisions and there is no need to forget all the hobbyists, yet some work is has to be done for speed, meaning rendering via gpu. Read this and you wonder no more why:
Still not convinced? Ok, then compare the good old cpu rendering to gpu renderer which is using even four graphics cards. You should be worried if it is ok for you to use months instead of hours just for a single rendering task.
While AMD combined cpu and graphics card, it is reasonable to make that system work with blender. Otherwise, in the future blender would be just a complex toy for no real use. Of course, we don't like that kind of scenario. All those guys developing blender really want to make it cool and handy tool. Even so, let's face the fact that for that purpose we should not ignore heavy users. By developing a lot of expert level features just for beginners is not reasonable. So, blender is really supposed to be professional too as well as for hobbyists.
Star Weaver wondered whether gpu rendering is capable of doing all required tasks:" I don't see how they're going to be able to help with ray tracing, caustics, radiosity, AO/GI...".
For a single frame this really might be a problem while it would require a lot of changes to blender's rendering pipeline. However, for animations gpu rendering is really essential. Parallel computing can be used like rendering farms. There should not be those problems you mentioned and your computer would render several frames at the same time.
It is clear that commercial software companies take the full advantage of the latest technology, or at least of the technology their customers are willing to buy. Community developed program like blender is multi platform, which is good, but for professional use speed is essential. No one can't afford to loose their customers and pay more for electricity. Note that this is not complaining. The technology arrived is new now it is a time to make good decisions. Basically, we choose users and the purpose of the blender by that gpu vs. cpu rendering. Why to bother developing expert level new features for beginners if it is not intended to be an expert level tool? It surely is great for now, and I'd love to keep it that way. Keeping things unchanged in this matter leads to the opposite result.