Metroid Prime gives you the option to scan many things. One area in the ship that was shown in the demo contained a grouping of enemies contained in some containment devices. Here's the information on them.

	Species: Sova Info: Native of Tallon IV.
	Species: Parasitic Larva Info: Harmless unless encountered in large numbers.
	Species: Fireflea Info: Native of Tallon IV.
	Species: Hard Shelled Metaree Info: Native of Tallon IV
	Species: Unknown Info: Unstable xenothropic lifeform in solitary holding. Unknown Phazon level.
	Species: This is a horribly mutilated Parasitic Queen. Info: Its mutilation is detailed here.
	Subject: Ridley Info: Weapon augmentation complete. Stinger ballistics are online. Plasma fuel cell is online. Cerebral casing is stable. Exoskeleton hermetic seal is holding. Umbilical retraction is ready to begin.

Yes, it's true. Ridley will indeed be in Metroid Prime. Here are some more images of the scan. Screenshot 1 | Screenshot 2 | Screenshot 3 | Screenshot 4 | Screenshot 5