Explicit Zend Framework support is probably the least important requirement since its very portable. Look for a host that has good up-time, responsive support, and can scale.
You can overcome some of the latency issues by using a content delivery network (CDN) to host your static assets. I don't have a specific recommendation, but I did get Zend_Application running on DreamHost for less than $2/mo http://www.dreamhost-promo-code.net/dreamhost-coupon.html - pw
