From Mahara Wiki
This is a stable release of Mahara 1.1 Sonorus. Stable releases are fit for
general use. If you find a bug, please report it to the tracker:
Please choose '1.1 stable branch' as the version of your bug.
This release includes an upgrade path from 1.0. If you wish to upgrade, we
encourage you to make a copy of your 0.9 website and test the upgrade on it
first, to minimise the effect of any potential unforseen problems.
This release includes:
Bugfixes to the 1.0 -> 1.1 upgrade for MySQL
If you have already installed or upgraded to 1.1.0, there is no need to upgrade to 1.1.1.
As mentioned before, when upgrading from 1.0, please attempt it on a copy of
your site first, to test that you will enjoy a trouble-free upgrade.