I just finished first order homogeneous equations, as well as my logcombine function, and I have pushed them to http://github.com/asmeurer/sympy/tree/odes-stable. So expect a major blog posting about them both soon (it is midnight right now, so bedtime, maybe tomorrow).
If you are a member of the SymPy project reading this, please, review my patches. I have already submitted exact equations and the logcombine function, and neither of them have made it in. And the more reviewing that there is, the better for my code.