I'm a couple of days late with this post, but it's very relevant to what this blog is all about, so I'm going to post anyway...
March 31st saw the retirement of the VCP310 exam for the VCP on VI3 (VCP3) certification, that was the last day anywhere that you could take that exam at a Pearson Vue testing centre, and quite a few did - Global Knowledge UK offer Pearson Vue testing at most of their training centres, and there were quite a few who had left it to the last minute to take their VCP310 exam.
If you are a VCP3 already, you will remain one, VMware don't retire certifications, only the exams that you have to pass to obtain those certifications. VCP3 holders can choose to "update" their certification to the VCP4 for vSphere, but they will have to attend an official vSphere: What's New course in order to qualify for VCP4.
If you missed the boat on VCP3, and I've already had emails from those who did, then VCP4 is now the only current VMware certification you can go for. If you've attended one of the VI3 training courses that qualified for VCP3, then you also have the option of attending the vSphere: What's New course or any of the other qualifying vSphere courses. If you didn't attend a VI3 course, you will have to attend a full course on vSphere such as vSphere: Install, Configure, Manage or vSphere: Fast Track.