To everyone saying that Maul showing himself was all part of the master plan, my question is HOW does it do so.
The Jedi knowing the Sith are back wouldn't seem to have any effect in how things play out.
The only change would be that it would have been Qui-gon training Anakin instead of Obi-wan. This may have lead Anakin down a different path but it seems unlikely.
Knowledge of the Sith didn't have anything to do with the discovery of the Clone army, that was found while searching for the assassin after Padme. It wouldn't necessarily have effected the spiral towards war with the CIS, they may just have had a different political leader than Doku. So war would still have occured, leading to Palpatine being given emergency powers. The Jedi would still have objected to him having them, and he would still be able to use that as an excuse to kill them. Palpatine would have still revealed himself to Anakin, and the end results would have been the same.
Meanwhile the Jedi would have been even more clueless about what was transpiring.
The Jedi's knowledge of the Sith's return played almost no role in the actual plot of the movies.
It lead to a war between the republic and the Separatists, lead by Count Dooku (and grevious but he didnt get much show till the cartoon). Which is what Palpatine wanted. If the war wasn't in such desparate stages, the Jedi Council would NEVER approve of the use of a clone army, and Palpatine needed the clone army for his master plan (killing the jedi).