I just noticed this little gem:

Glyph of Mana Tide Totem (Req. lvl. 40) - Your Mana Tide Totem grants an additional Spell Power of each target's maximum mana each time it pulses.
Holy crap, so wait a minute.... if mana tide stacks does that mean if all my shaman throw out manatide we all get stacking spell power bonus? That will be so damn awesome!