OpenRAW

It has been found on Russian camera-dedicated forum, that some camera manufactures pre-process raw data from matrix before it is stored as RAW file.
http://forum.ixbt.com/topic.cgi?id=20:20473-12#386

They noticed WB adjustment results differed a lot in Pentax own software and ACR, dcraw, UFRaw.
This leaded to suspicion WB settings are already applied to the RAW file. They wrote a program to extract data from RAW and show channel histograms. It happened RAW files shot with different WB settings differed not only in exposures, but in channels.
* AWB: http://img89.imageshack.us/img89/7518/imgp9705pefsrl2.jpg
* Daylight WB: http://img291.imageshack.us/img291/9208/imgp9706pefszp6.jpg
* Tungsten WB: http://img149.imageshack.us/img149/3917/imgp9707pefssi3.jpg
* Manual WB (grey card): http://img148.imageshack.us/img148/3273/imgp9708pefsff4.jpg

So it is the fact now - Pentax applies WB to RAW data.

Minolta/Sony camera RAW results depend on the colour space of the shot. It can only happen if colour space conversion is applied before written RAW data.

Canon has its own RAW suspicions.

So it is another problem of RAW files: the manufactures should provide pure RAW without pre-processing.