There’s not supposed to be any generated password upon activation in 1.1.3. No passwords are ever sent by email in 1.1.3. You may have missed something in the upgrade.
We had noticed that the welcome email includes a wrong password, perhaps because of different encryption between WP and BP. The password that was entered upon registration still works.
Note that in 1.1.3 the WPMU is disabled by default. To bring it back you have to remove a function from the core files.