Chpwn, one of the ProSwitcher developers, has released Infinidock for iPhone/iPod Touch.
Infinidock let you to add as many applications as you want on your iPhone dock and scroll them horizontally just like Springboard pages navigation. Simply drag your desired apps to the dock and swipe on the dock horizontally to scroll between dock apps.
Infinidock has no icon on the Springboard. However, you can access Infinidock settings from Settings app.
Infinidock can be purchased from Cydia Store for $0.99.