I think since Skype came along, there are more trainers (including myself) who are adding this service as part of their training offerings. I do agree with Michael, that it is best done one on one. Also, there are many people who are busy in their daily life and a Skype or online training might be a great way for them to get their workout in.
I think online personal training can be a great tool. I’ve recently created http://biomechanicallyfit.com/, which I offer two package options individuals can choose from. I offer 100’s of exercises and workouts they can view and follow if they would like. I also use gotomeeting to connect with clients throughout the month. Quality will never be the exact same since you won’t have that in person one on one feel but you can’t have everything especially at a lower cost.
yes, there is more talk about it, and if other people can make it work for themselves, all the power to them. I cannot see how it can be of equal quality, particularly at the beginning stages of training. During the assessment and the first few workouts, I learn a lot about a client, and hand-on is often necessary to correct proprioception deficiencies.
Where I can see a place is in a scenario where I know the client and am comfortable that s/he will execute correctly at a distance.