% /java/re/jdk/7/promoted/all/b02/binaries/solaris-sparc/bin/java -XX:+PrintCommandLineFlags -XX:+UseConcMarkSweepGC -XX:CMSYoungGenPerWorker=4m -Xms16m -Xmx16m -version

-XX:MaxHeapSize=16777216 -XX:+PrintCommandLineFlags -XX:+UseConcMarkSweepGC
java version "1.7.0-ea"
Java(TM) SE Runtime Environment (build 1.7.0-ea-b02)
Java HotSpot(TM) Server VM (build 1.7.0-ea-b02, mixed mode)

% /java/re/jdk/7/promoted/all/b03/binaries/solaris-sparc/bin/java -XX:+PrintCommandLineFlags -XX:+UseConcMarkSweepGC -Xms16m -Xmx16m -version

-XX:MaxHeapSize=16777216 -XX:+PrintCommandLineFlags -XX:+UseConcMarkSweepGC
Error occurred during initialization of VM
Incompatible initial and maximum heap sizes specified

But the following is a workaround of sorts:
% /java/re/jdk/7/promoted/all/b03/binaries/solaris-sparc/bin/java -XX:+PrintCommandLineFlags -XX:+UseConcMarkSweepGC -Xms16m -Xmx16m -XX:+CMSUseOldDefaults -version
-XX:+CMSUseOldDefaults -XX:MaxHeapSize=16777216 -XX:+PrintCommandLineFlags -XX:+UseConcMarkSweepGC
java version "1.7.0-ea"
Java(TM) SE Runtime Environment (build 1.7.0-ea-b03)
Java HotSpot(TM) Server VM (build 1.7.0-ea-b03, mixed mode)

This is a regression as a result of the changes in:

6465357 CMS: default choice of NewSize can cause obscure startup failure w/small -Xms