Based on a comment made by a colleague, I followed up with someone with VMware Education, who quickly got back to me and said that
VMware is apparently planning to discontinue "VMware vSphere: What's New" at the end of 2010, though I am also under the impression it's not a done deal. That would be the end of the cheapest option for existing VCP3 holders to qualify for the VCP4 certification (after passing the VCP4 test, of course).
If you were planning to take "VMware vSphere: What's New" in 2011, you should contact VMware Education immediately to learn your options.
Corrections welcome if someone has better information. I was not aware until today that this course was heading to the dust bin at the end of 2010.