Edit, April 21: Someone re-created the tag the other day. I've gone through and re-tagged the afflicted questions once again. Two more votes are needed to approve the zend tag as a synonym of zend-framework. This will prevent the tag from being recreated again.
I have completed the Zend-ectomy. Of the ~1,300 questions tagged zend, 850 of which have now been re-tagged by hand into other specific and correct tags, including zend-server, zend-server-ce, zend-studio, zend-debugger, zend-guard, zend-certification and a partridge in a pear tree.
Oh, and zend-framework. Lots and lots of Zend Framework. As it happens the remaining ~450 questions are all also tagged zend-framework*. While there is a small chance that the standalone Zend tag in those specific questions references something other than Zend Framework, it is highly unlikely.
Therefore, I request that the zend tag be completely removed from all questions.
Zend Technologies Ltd. produces multiple products, but they are rarely the subject of the tag. Instead, people call Zend Framework "Zend", and thus frequently end up mis-tagged. Given this, I would also like to request that the tag become an alias of zend-framework, as people will surely continue to use it otherwise. The two tags are effectively synonymous.
* Except for that single closed one at the top, which I am unable to retag.
Edit, April 4: Given no response from the SO moderation team, I'm just going to finish up the remaining ~450 questions myself.