What is Xtend supposed to provide that Scala doesn't already provide? It looks like their setting out to solve a subset of the problems that Scala deals with already.
Unlike Scala it compiles down to Java. Depending upon how readable and sane the generated code is, I could see people working in organizations where Java is mandated write code in Xtend and then commit the generated Java code or use the generated code as base for code that get committed to official channels. Although I'm skeptical of how readable the Xtend generated Java is.
Doing so would mean it would need to be super friendly going the other direction. It'd be really annoying working in one language, compiling to java, having someone modify that java, and then needing to read and work through everything in java now.
I've found the open source version of intellij + scala plugin most impressive. Reliable code completion and everthing i've come to expect from a java IDE. I've had much less success with scala plugins for Eclipse and Netbeans. Without the intellij plugin for Scala I wouldn't have chosen Scala.