Calculations:

Conversion Rate = Conversion / Visitors
Lift = (TreatmentN Conversion Rate / Control Conversion Rate) -1
Variance = Conversion Rate * (1 - Conversion Rate)
Standard Deviation = sqrt(Variance)
Standard Error (control) = sqrt(Control Variance / Control Visitors)
Standard Error (treatmentN) = sqrt((Control Variance / Control Visitors) + (TreatmentN Variance / TreatmentN Visitors))
Signal-to-Noise Ratio = (TreatmentN Conversion Rate - Control Conversion Rate) / TreatmentN Standard Error
Confidence = 1 - TDIST(ABS(TreatmentN Signal-to-Noise),(TreatmentN Visitors + Control Visitors - 2),2)

Note: For a more indepth explanation of the statistical formulas used and for a walk through example, please refer to the post Understanding Statistical Significance with Omniture Test & Target