If this is the first time you're hearing about the Worksheet, make sure you check it out. All feedback is that it is an exceptional productivity booster for your daily Scala coding.
In a nutshell, a worksheet is a Scala file that is evaluated on save, and the result of each expression is shown in a column to the right of your program. This makes it easy to see the execution results of each statement in a Scala app without having to step through a debugger. Worksheets are like a REPL session on steroids. The Scala Worksheet also supports editor completion, hyperlinking, interactive errors-as-you-type, and auto-formatting. This new release includes a number of fixes related to the worksheet instrumentation.
The worksheet plugin is available for both Scala 2.9 and Scala 2.10.0-RC1. It can be installed on both Eclipse 3.7 (Indigo) and Eclipse 4.2 (Juno). Get started by either downloading the ready-to-use Typesafe Scala IDE or reading the Scala Worksheet installation instructions.
For more details about this release, check out the Scala Worksheet article on the Scala IDE blog.
Enjoy the latest release and provide any feedback via the scala-ide-user mailing list.