To me, this is an excellent idea! Lots of little, nifty things like this is in my experience what helps newcomers instantly start liking Inkscape. The color boxes at the top right of the Inkscape window only opens my preferences dialog, though. I would have expected the color dialog to appear.

Cheers, Jimmy Volatile.

I actually liked this idea, as I've always been slightly surprised by the initial result whenever I start drawing something in Inkscape, and this would make that absolutely clear. So I've made an initial patch that implements this (if I missed a tool, it's easy to add one, just needs a small change to TOOL-context.cpp and some recoloring of cursor-TOOL.xpm).

I'm interested in people's experiences, so I've attached a patch and uploaded a Windows build to:
http://home.hccnet.nl/th.v.d.gronde/inkscape-color-cursor.zip
(just inkscape.exe, so backup your current inkscape.exe, extract the zip and your good to go)