Additions in 0.10 include plotting support, matrices and linear algebra functions, new root-finding and quadrature algorithms, enhanced interval arithmetic, and some new special functions. Many speed improvements have been committed (a few functions are an order of magnitude faster than in 0.9), and as usual various bugs have been fixed. Importantly, this release fixes mpmath to work with Python 2.6.
For a more complete changelog, see: http://mpmath.googlecode.com/svn/trunk/CHANGES
Also be sure to check out the function gallery! It contains pretty colors ;-)