In the past decade, CMB experiments have discovered a new contribution to Galactic emission which rises above free-free, synchrotron, and dust emission at microwave frequencies. The leading explanation is that this signal comes from very small, spinning dust grains; however, this is not very firmly established and there are alternative explanations. Some of these possibilities can be distinguished by measuring the microwave polarization of the signal. I describe an ongoing project to make these measurements with the GBT.
"MUSTANG: GBT First Light at 3mm, Current Status, & Plans" has been postponed.