VMware announced this clarification to licensing servers with a single processor on the first of April, and I thought it was great clarification. I know that in the past, when customers have asked to run VMware ESX Server on a server with a single CPU installed (1 or more cores), we have, on a case by case basis, allowed customers to split the licenses. This happened for a lot of customers that had branch offices, or retail outlets where it made sense to run single processor servers.
Now, we have publicly clarified this via our EULA. To do this, you need to have your VMware ESX Server managed by a license server, and you still have to buy licenses in increments of two, but I think this is a great step forward.