Oracle has released the Oracle 188.8.131.52 April 2007 Critical Patch Update (CPU) Windows 32-bit patch much ahead of scheduled April 30th date. Media reports (here) were critical of Oracle's failure to release this patch in a timely manner due to the severity of one of the bugs affecting the database running on the Windows platform.
However, the Oracle E-Business Suite patch available matrix has not yet been updated (Metalink Note ID 420072.1) to reflect the change and still has the April 30th date. It is most likely just an oversight, although the issue with the patch may be related to the Oracle E-Business Suite. If you are planning on or need to apply the patch this weekend, you should open a TAR with Oracle to verify the correct course of action.