What program will do 4 axis continuous machining?
Meaning you have a 3d model of lets say a persons head and you want to machine it into a block of aluminum. Most programs make you index and slightly turn the table then run a roughing code then repeat.

Is there something that can take into account the safe zones and not run into the edges of the stock?

Visualmill and rhinocam are two that I know of.

DeskProto will too, but it only works with .stl's.

Pretty much any CAM over $6500 will do it.
OneCNC starts about there with 4 axis.
Prices skyrocket pretty fast and don't forget a lot of the big buck guys also have yearly maintenance fees.

BTW I use VisualMill

There is the CNC Toolkit for GMAX does 4 and 5 axis stuff.
http://www.rainnea.com/cnc.htm
http://groups.yahoo.com/group/CNC_Toolkit/?yguid=113406470

Not commercial grade software last I looked at it but it can be made to work and it is cheap.