Glassfish: Exception in thread "main" java.lang.UnsupportedClassVersionError: com/sun/enterprise/admin/cli/AsadminMain (Unsupported major.minor version 49.0

Look through you PATH variable and correct the route for the right the java version. In my case I had a jre1.3 in my path :S, so I changed it to jdk1.6. That worked smoothly :D

References:
http://techtracer.com/2007/10/10/resolving-the-unsupported-majorminor-version-490-error/