thanks for pointing me into the right direction. This did not work at first ether but it was my fault. I had \setupinterlinespace[big] before \setupbodyfont. This will reset the interlinespace. However, \setupinterlinespace[line=1.7em] before \setupbodyfont works.
Still, \setupinterlinespace[big] does not change anything in the publication list.
You have to make a distinction between a absolute and a relative value for the interlinespace.
With \setupinterlinespace[line=12pt] you set a fixed value of “12pt” for the distance between lines while \setupinterlinespace[big] use these value and multiplies it by the factor “1.5”. When you place a register (e.g. your bibliography) context goes back to the fixed value for the interlinespace and the factor is ignored.
Thanks for the explanation, I didn't know that the scale factor is ignored in the bibliography intentionally.
When you want the bigger linedistance for your whole document change the absolute value to 4.2ex (the default value from context is 2.8 multiplied by 1.5 from big).
All right, I will do that. Florian