Yes, that would be great!  I have some scratch work for the raised cosine and root-raised cosine FIR filters, but they're not ready for contributing to scipy.  If you have code in pretty good shape, these would be nice additions to scipy.signal.

The first thing to think about is the API.  What is the API of your code?

A possible design is similar to the Savitzy-Golay filter implementation.  It's a very basic, function-oriented API.  One function, savgol_coeffs, provides the FIR filter coefficients, given the number of taps and the parameters of the filter.  Another function, savgol_filter, takes an input array along with the filter parameters.  It computes the coefficients and applies the filter.  It is really just a convenience function: it calls savgol_coeffs to compute the filter coefficients, and applies the filter using a convolution (the only complication is that it provides several options for handling the edges of the input).  Even more basic are the functions for FIR filter design using the window method.  The functions firwin and firwin2 compute the filter coefficients, and leave it up to the user to convolve them with their signal.

Looking forward to hearing more.

Warren