The archetypes' prototype poms refer to the out-dated package names ch.epfl.lamp.sdt... from the Scala IDE tooling, which have been succeeded by org.scala-ide.sdt.core (at least) in recent builds. As result, Eclipse projects created from these archetypes are not built properly.
I added a patch to fix this issue for .classpath and .project generation.
Imported from Assembla: http://www.assembla.com/spaces/liftweb/tickets/879
The current 2.5 archetypes are updated and don't have this issue.