SymPy 0.7.3 is now available for Maemo 4 & 5. It has improved integration with Risch integration algorithm, etc, so it is recommended to use SymPy 0.7.3 on Integral. The loading time of Integral is increased :
Maemo 4 : 22s (SymPy 0.7.3), 16s (SymPy 0.7.1);
Maemo 5 : 9.5s (SymPy 0.7.3), 7.0s (SymPy 0.7.1);
but it is worth upgrading.
To upgrade to SymPy 0.7.3, install the new version of "SymPy interactive shell" (0.7.3) using the application manager with "extras" repository enabled on Maemo 4 and "extras-devel" or "extras-testing" repository enabled on Maemo 5.

I will later release a new version of Integral depending on SymPy 0.7.3 and with new features.