I raised this question with JMP support and received the following which I have slightly paraphrased:
The smoother utilized in the Graph Builder platform is a cubic spline with a lambda of 0.05 and standardized X values. The same spline can be obtained through the Bivariate platform by selecting Analyze > Fit Y by X, supplying the Y and X variables, and clicking OK. On the resulting Bivariate report window, select Fit Spline > Other from the popup menu. Then supply a smoothness parameter (lambda) of 0.05, and check the Standardize X box.
This information is from the JMP Statistics and Graphics Guide for version 8.0.2 and this info is found on pages 929-930 in Chapter 43. This is in the section on "Changing the Graph Element".
The "standardization of X" has the same effect as subtracting the mean and dividing by the standard deviation for the X variable and then fitting the spline. The only difference is that in Graph Builder and the Fit Y by X platform, the data is still plotted on the original scale rather than the standardized scale. Using standardized X values seems to smooth out the fit a little