Google is once again sponsoring a Summer of Code (SoC). For the past several years, the SciPy community has participated in the SoC program through the Python Software Foundation (PSF). Past projects have included a new testing framework, numerical optimization code, machine learning code, and improved support for NumPy in Cython. Most students have remained very active in the community and continue to be major contributors to the SciPy community.
To see a list of possible project ideas please see the PSF's SoC wiki. A number of students have all ready expressed interest in working on a SciPy-related project this year. If you are interested, the best place to discuss ideas is on the NumPy and SciPy developer mailing lists.