Mygazines is like the youtube of magazines. It allows you to read and store your magazines online. But they are in a little bit of trouble with the copyright infringement notices flying across it right left and center. Its a really neat concept, as you can read magazines that you would not get in your local store.
They post the complete magazine with all the adverts intact so that should in a way be good for the publishing house. In the long run if they survive they should only be like a repository of old magazines. In any case most magazines have a shelf life of no more than a month. If they start storing older magazines with all the adverts intact it should work in the favor of the publishers.
Also people would be able to sample magazines which they would not otherwise. Its almost like online music. If someone likes the music they will pay for it. Same goes for a magazine. I loved reading the magazines online but for most other times I would like a physical copy, and I won't mind paying for the physical copy.