Since more user, just like me, are struggeling with gammacorrection here are two solutions:
1) Manually correct you RGB with the next formula:
Corrected R = 255 * (uncorrected R / 255) ^ 2.2
Corrected G = 255 * (uncorrected G / 255) ^ 2.2
Corrected B = 255 * (uncorrected B / 255) ^ 2.2
* 2.2 is used as gamma here
2) I used a nodes for the three individual colors RGB first. But this made life even easier. Add the gammacorrecternode to your surface. Change to value to 1/2.2 (=0.4546), add a colornode and attach.
The best is by selecting all materials and disable the nodes, you've got gamma 1 back. So now you can see the actual color as you adjust it, and use these for lw-native renders.
http://www.auroragrafx.com/LW_Plugins/gammacnode.zip
Since OB3 uses nodes this works like a charm.
Sure, disabling all nodes on more complex nodebased materials will show up different. But the idea of quickswitching is ideal for me.