The video on the site Stewart Peterson referred to is pretty scary alright. There are other websites with collections of photos.
Wind turbines require brake systems to protect them from over-speed conditions. If the brakes don't do the job, something's going to break eventually. The brakes are powered with stored energy (like springs, or hydraulics with a gas accumulator) to lock the rotor in the event of a power failure.
A related aspect is that large wind turbines must be actively steered into the average wind direction. If the grid fails, most large wind turbine installations do not have a back-up power supply that will orient them and facilitate start-up. They cannot "black start" if there is an outage.
The energy transmission question really relates to where they are located. Most often wind farms are built in remote locations where the power grid is thin -- it was designed to deliver power to small load centres, not connect to sizeable generation sources. Consequently there is a significant cost to install power lines and switchgear to accept the generated power.
This transmission cost is not necessarily absorbed by the owners of the wind farm. The pay back rate on the required installation is limited because of the low average power capacity that most wind installation realize (e.g. 30% + or - 10%).
Wind turbines are also vulnerable to lightning strikes. This problem should be solvable with appropriate technology.
Some large wind turbines use gears to increase the rotor speed to match that needed by the generator. These large "transmissions" have had some problems. This is not a surprise because similar problems show up in helicopters and ships.
Others have many generator poles and some scheme I haven't read about that adapts to the wind speed.
I recently learned that three 800 MW wind generators were installed on San Cristobal Island in the Galapagos in a hybrid configuration with diesel generators. http://eolicsa.com.ec This is an ideal application since the diesel fuel consumption will fall as the wind generators pick up the load. Apparently it was inspired by the grounding of the oil tanker "Jessica" in January 2001. Wind generation will reduce the amount of oil needed, but not eliminate it. I heard on a radio program that there is a proposal to convert to bio fuels. I'm not sure it will make any difference when the next spill occurs. Of course, the biodiesel might be more enviro-friendly, depending on the source.
Apparently, each of these wind generators has a foundation of 250 to 300 cubic metres of concrete.
I wish Canada was putting wind generators in our remote communities that rely on diesel generators. However, I don't know how much work has been done to support operation in the very cold conditions up North. It would make a lot more sense to me than wind farms in Ontario.