They've been free for quite a while. There's now some nice Electronic Flightbag to view itin FS9. I've been using the FSWidgets EFB since it came out last October. www.fswidgets.com/products_efb2004.php
Thanks for the HU, Tom, I'll have to check that site out.
I also have been using FSWidget's EFB and highly recommend it for anyone looking for such a utility. I already have several hundred charts, plates and airplane manuals stored in it. It seems to only be limited by the amount of hard drive space you have.
As the url suggests, this will tell you how to overlay sectional charts onto Google Earth. After selecting a chart to overlay (you can do one at a time), use the slider on the left sidebar to adust transparency.