Ok, so I don't work for VMware, but I'm heavily involved job-wise and community-wise in VCP. Given your VCP3 and vSphere 4: What's New attendance, your options are as follows:
If you only want to gain VCP4, pass the VCP4 exam. The retirement date for the VCP4 exam has not yet been announced, which would explain why you can't find such a date.
If you only want to gain VCP5, attend the vSphere 5: What's New course and pass the VCP5 exam before the end of February. From March 1st onwards, you would have to attend vSphere 5: Install Configure Manage or vSphere 5: Fast Track regardless of whether you have attended vSphere 5: What's New or not.
If you want to gain VCP4 and VCP5, pass both exams before the end of February. If you only manage to pass the VCP4 exam before the end of February, you will have to attend vSphere 5: What's New and pass the VCP5 exam to gain VCP5 certification.
Scott.