Before anyone bites off my head: No, this is not about warmages and rainbow servant's "cleric spell access" class ability though the question is related to latter. 
The description of class ability states:
Cleric Spell Access: A 10th level rainbow servant can cast spells from the cleric list, even if they don't appear on the lists of any spellcasting class he has. Such spells are cast as divine spells if they do not appear on the sorcerer/wizard or bard spell lists...
Now SRD has this to say about divine spells:
The relevant ability for divine spells is Wisdom. To prepare a divine spell, a character must have a Wisdom score of 10 + the spell’s level. Likewise, bonus spells are based on Wisdom.
Although the class ability description says nothing about it, the above quote leads me to believe that a rainbow servant would need to have high wisdom score in addition to his or her relevant arcane spellcasting score. It also leads me to believe that the save DC is wisdom based.
This is furthermore supported by the arcane disciple feat (also from complete divine) that grants arcane casters access to domain and its spells but only if they have high enough wisdom.
I'm curious to know how other people have interpret this or if there is an errata that clarifies it (and the rainbow servant spell progression). I have read posts about "errataed" version of the rainbow servant but I haven't found it anywhere - It's certainly not on WoTC CD errata.
Any thoughts?

The description of class ability states:
Cleric Spell Access: A 10th level rainbow servant can cast spells from the cleric list, even if they don't appear on the lists of any spellcasting class he has. Such spells are cast as divine spells if they do not appear on the sorcerer/wizard or bard spell lists...
Now SRD has this to say about divine spells:
The relevant ability for divine spells is Wisdom. To prepare a divine spell, a character must have a Wisdom score of 10 + the spell’s level. Likewise, bonus spells are based on Wisdom.
Although the class ability description says nothing about it, the above quote leads me to believe that a rainbow servant would need to have high wisdom score in addition to his or her relevant arcane spellcasting score. It also leads me to believe that the save DC is wisdom based.
This is furthermore supported by the arcane disciple feat (also from complete divine) that grants arcane casters access to domain and its spells but only if they have high enough wisdom.
I'm curious to know how other people have interpret this or if there is an errata that clarifies it (and the rainbow servant spell progression). I have read posts about "errataed" version of the rainbow servant but I haven't found it anywhere - It's certainly not on WoTC CD errata.
Any thoughts?