sbt 0.5.6 includes support for the latest versions of the Scala test
frameworks and for Scala versions 2.7.2 to 2.7.7. The launcher did
not change, so the only reason to download the new launcher is to get
0.5.6 as the default sbt version and 2.7.7 as the default Scala
version.
To make an existing project use 0.5.6, do the following at an sbt prompt:
set sbt.version 0.5.6
reboot
Thanks,
Mark