This is the first bugfix release in the 0.8 series, to address a critical regression on older versions of Django.
Major changes are outlined below. A full list of changes can be found on the repository.
There was a critical regression with South 0.8 and any version of Django below 1.5 due to a misimplementation of the index_together code - this has now been fixed.
The keep_default argument to add_column has been working differently in different backends for a while, so it is now ignored everywhere and defaults are never kept in the database.