Here is a gallery of pictures using an iphone and the instagram application ive used a few of the filters to show what is possible Here is the list of filters:
History
X-Pro-II
Lomo-fi
Earlybird
Sutro
Toaster
Inkwell
Walden
Hefe
Apollo
Poprocket
Nashville
Gotham
1977
Lord Kelvin
Every time you modify a picture with instagram it is saved to you camera roll and to the instagram website. You can also share them on twitter Facebook tumblr posterous and a few other places.
I highly recommend this app. It's fun and easy to create a good looking picture with your iPhone. And besides, the nostalgia factor is cool.