Actually there is Zend Optimizer and Zend Accelerator. Zend Accelerator is a retail product with the lowest possible price (That I am aware of) being $295.00 per CPU per server and that is without updates or support. Zend Optimizer only optimizes the code, it is not an accelerator.
Together both Zend Optimizer (which is free) and Zend Accelerator smoke any other PHP accelerator/caching software including Turck, MMCache and Ioncube. I would assume that is because Zend wrote the PHP language to begin with...
I would ask the specific questions to the hosts you consider. Unfortunately I don't know for sure of any hosts that use that combination that I would be permitted to recommend. I would also bet that you wouldn’t find this type of software on your run-of-the-mill budget hosting either.