Well, the reason the skystream works is because it has its own voltage sensor for the batteries that you buy separate. When the batteries reach full charge, the windmill receives signal to power down and put on the brakes. Thats why the skystream system works.
When researching this concept I found 2 other things that may interest you guys.
#1) the Sunny Island system works exactly like this through AC Coupling, in essence allowing you to use Grid Tied 600v inverters instead of 120v charge controllers. The sunny island ties in directly to SunnyBoy WindyBoy grid tie inverters using them as charge controllers when the grid is not functioning.
#2) I also found an AC Coupling diagram for Xantrex XW inverters that showed a feature I was not able to find any info on. Apparently you can take a Xantrex GT inverter, connect it to an XW Inverter on the AC out side. And connect the two together with a communication cable allowing the XW system to shut down the GT in the event that the Batteries reach a full state of charge.
Both concepts are probably worth further investigation. It would seem to me that this method of setting up a solar power system, grid tied with backup, is likely much simpler than using charge controllers and would effectively eliminate charge controllers from the setup. Even though, apparently, you can still use them if you want to. Also I think I can use this setup to have a negative ground battery based backup connected to a positive ground solar array and not lose any efficiency in panels manufactured like my "Sunpower" solar panels.