What went free with v6 are basically
sandbox
print to scale (and other print) options - in v5 it was limited to "fit to page"
2d graphic export optiions - in v5 it was limited to screen resolution
animation export
(afaik) the ability to use rbs plugins
What is still "missing":
Export models in 3DS, DWG, DXF, OBJ, XSI, VRML, and FBX file formats
LayOut (and lately StyleBuilder)
Location tab in the Model info (Win only - funnily the Mac version has it - but Jim wrote a plugin for that already)
The little
http://download.sketchup.com/sketchuphelp/gsu6_win/Content/Z-images/A-Welcome/welcome-Plus.jpg
image however appears all over in the SU Guide according to v5. Google forgot to update this part of the guide (and a whole lot of things are also missing there - just think about intersect with selected or intersect with context which came with SU6).