Scala's version fragility make the Enterprise argument near impossible

An attribute of Scala is that the Scala compiler generates fragile byte-code. This means that all the code in an executable (JAR or WAR) must be compiled with the same library and compiler versions. If you're using Scala 2.9.1 in your project, you must compile against a version of Lift that's compiled against Scala 2.9.1 and all the Lift dependencies must also be compiled against that version of Scala. This is a reason that Lift has precious few Scala library dependencies. It's also a reason that Lift is sprawling... there are a lot of modules in Lift that need to be cross-compiled and rather than having an external ecosystem of modules, we need to make them part of Lift to make sure they are all compiled against all the versions of Scala that Lift supports.

The by-product of this issue is that it's nearly impossible to test Lift or a Lift-based app against a pre-release of Scala. This is one of the many reasons that there's almost always a "critical bug fix" release of Scala a few weeks after any major release. The first chance that the broader community gets to use the ecosystem of Scala libraries and frameworks is after a release and after the cascading compilation/test/release