The only silly question is the one you never asked :)
After they changed healing spells to use Spell Power instead of Bonus Healing, they scaled Spell Power by a fixed amount on Heals. This amount is normally referred to as 1.88. The exact origin for 1.88 is the itemization cost of Spell Power (0.855) divided
by itemization cost of Bonus Healing (0.455). So every heal gets 1.88xSpell Power added based on their coefficient.
1.5/3.5*0.855/0.455 = 0.8053, or 80.53%.
Live results may vary from Beta results, but remember, we are currently aiming at getting things right for WotlK @ level 80. On PTR Focused Power also boosts PW: Shield by an additional 2/4%.
I redid all my testing on PTR yesterday, and the formula I came up with was:
Base Absorb (BA) = 1265
Improved PW: Shield (IP)
Spell Power (SP)
Borrowed Time (BT)
Focused Power (FP)
Twin Disciplines (TD)
[BA*(1+IP*0.05) + SP*(1.5/3.5 + BT*0.08)*1.88]*(1+IP*0.05)*(1+FP*0.02)*(1+TD*0.01)