java 7 update 4 is a stable release but its is currently targeting developers (programers using java language not the one who are creating the jre or jdk)
they do this so that developers can try it first before the consumer or java app clients, also to help developers port their application to java 7 and ensure their programs are compatible
dont worry about it yet eventually your auto update will upgrade it in time

java 6 end of life is on nov 2012 so there still a couple of month before you really need to upgrade