As Always the answer is 'It Depends'.
If you are a consumer and the patch is security related do it now.
If you are an enterprise and you are running an application server and the patch details do not mention a security vulnerability that you are likely to hit (User running malicious JNLP application) you can hold off. If the 'patch' is adding new functionality such as Java 1.6.0 Update 10 (Update N) then you can maybe hold off.
In general updates to a certain Java version (1.4.2, 5, 6, 7) should be API stable and ok to update, but depending on what your application does to java you may need to test or hold off.
For instance recently Oracle changed some metadata about the HotSpot VM in a patch which caused the Eclipse IDE to fail.
99 times out of a 100 the Java patches should be API stable and have non-breaking changes.