[Erosennin900]

Most of the village elders know about Naruto's dad being the 4th but they tend to keep quiet.

And the fight was epic!! Jiraiya took out numerous boss summons and killed Pein 4 times! (the three original bodies + Fuuma Pein)

We saw Hermit mode and Ultimate Rasengan!
In my opinion nobody could have fought better than Jiraiya in that battle.

I also found a few of Jiraiya's better techniques and made a list:

Gama Daira Kage Ayatsuri no Jutsu - (Toad Flat Shadow Control Technique)
Gamaguchi Shibar - (Toad Mouth Binding)
Gamayudan - (Toad Oil Projectile)
Katon, Gamayu Endan - (Toad Oil Fireball)
Katon, Goukakyuu no Jutsu - (Great Fireball Technique)
Katon + Fuuton, Senpou Goemon - (Hermit Art Boiling Oil)
Senpou, Kebari Senbon - (Hermit Art Thousand Hair Needles)
Sennin Moodo - Hermit Mode!
Doton, Yomi Numa - (Swamp of the Underworld)
Oodama Rasengan - (Big Ball Spiral Sphere)
Ninpou, Hari Jizou - (Needle Guardian)