Groovy is a dynamic language for the Java Virtual Machine. But its runtime metaprogramming capabilities require dynamic dispatch. Dynamic dispatch is slow and does not allow compile time checks. Groovy++ tries to combine Groovys expressive syntax with statically typed code, one of the advantages Scala offers.
Learn more at:
http://groovy.dzone.com/articles/sneak-peak-groovy-what-it-why
http://groovy.dzone.com/news/alex-tkachman-static-groovy
http://code.google.com/p/groovypptest/