And I think we should hold off using string interpolation (even though its severely cool) for now because 
1. It causes inconsistencies with other strings in the same file (unless we go through the effort of actively changing all the files). 
2. Since we just converted to Scala 2.10 in Spark 0.9, there maybe a lot of changes that we want to merge back some of the current changes to the Spark 0.8 branch. It may not be a good idea to immediately start using string interpolation which will make it harder to merge back.

So I think we should hold off widespread use of string interpolation until after 0.9 release.