Can Glimmer be used with a Java project despite the fact that its syntax is in Ruby?
Absolutely. In a desktop application where the domain model is fully written in Java, Glimmer can be used to author the desktop user-interfaces declaratively. This is similar to how XHTML is used to author web user-interfaces declaratively for web applications.
Can Glimmer be used with Eclipse RCP?
Yes. Views, Editors, Wizards, and other RCP components can have the UI written declaratively in Glimmer's syntax, invoked through JRuby from Java's side.