The method getCommonBasedir in class org.apache.maven.shared.release.util.ReleaseUtil runs into the Exception:
java.lang.StringIndexOutOfBoundsException: String index out of range: -1
... while comparing pathes with small and capital lettes for Windows drives.
e.g.: C:\WoRkInG\root\project1 has no common base dir with c:\working\root\project2
but it should have c:\working\root as common base directory.
A patch and a test for that bug is attached.
I do have the problem with version 2.0 but I fixed it in trunk for now