I don't know how long this has been the case, because I haven't completely respeced a character's enhancements in ages but just yesterday I respeced by 23rd level clerics enhancements and noticed that her prestige enhancements gave no list or indication whatsoever as to the requirements to achieve them (good thing I wrote her previous enhancemnts down). This was with even Show Unavailable checked. Also most or all of the possible enhancements that use Turn Undead charges such as Cleric Divine Light, Cleric Divine Might, Cleric Divine Cleansing were all labled Unknown and had to be opened to see what they actually did. I had Collapse All checked for quick viewing purposes when I noticed this. This was on the live server.
I hope this was just because it was a respec. If not, than if anyone new to the game was trying to acquire their cleric prestige enhancement they'd have to research the requirements from some other source than the enhancements themselves.