Are EnCase and FTK software available for the Mac? or do they have to run on Windows systems?
Windows only. There is a Mac forensic tool, and it's been looked at in the reviews section of the site.
Or you could use bootcamp …
About the closest encase/ftk like Mac tool is Macforensicslab from SubRosa. I had beta'd it and it was pretty good. It's also cross-platform analysis capable and runs on Mac and Windows.
You may want to look at Blackbag as well. It is more modular than Swiss-army knife style but is more than capable. It is afaik Mac analysis targeted only.
Ftk Imager for Mac is available although this is command line based no GUI
Aaron
Actually we have released
Drew