In reply to baridude:
Eric,
I have this article on program blocks. Coincendently, there was this recent post as well on the VerificationGuild.
If you notice, all the OVM/UVM examples simply ignore them, which I take to mean the committee didn’t feel they were necessary either.
As for clocking blocks, there is one useful application for making it easier for the testebench to procedurally assign wires. I wrote about this in a recent DVCon paper.