Iulian, thanks, Aptana and Scala IDE take turns hijacking default editor type, so do not play well together.
As a workaround I have Aptana standalone for hacking on markup, and Scala IDE for all Scala code, including Play templates. Not ideal, but manually typing out XHTML markup is quite annoying, arguably worse than blind coding in Play templates (which I've been doing for nearly a year now) since SBT can at least provide some voluminous stack traces to slog through.
re: WTP integration help, already was asked to help out with Kepler -- tough times on the IDE front, everybody and their brother commits to scala.lang ;-)
Hopefully I can come up for air soon from current project and chip in somehow; Scala IDE has been my gateway to learning to Scala.