Transcript, taken from Halo wiki:
-White light fills the screen
343 Guilty Spark: "Construct, who is your maker?"
Unkown Construct: "Silence of pain is prepared, Oracle."
-Light fades to show the unknown construct, which appears to made of a column of light in various colors
Unknown Construct: "I am unworthy. I was never made."
343 Guilty Spark: "Never made? But you are right here. Where you should not be."
-View now of 343 guilty spark
343 Guilty Spark: " Tell your charger's to ceace ther efforts immidiately. Quarantine must not be violated."
-Now viewing a CCS-Class Battle Cruiser that is close to Installation 04
343 Guilty Spark: "Construct, respond"
Unkown Construct: "Jumbled Glass, familiar terms. I serve none so weak, Oracle"
-Screen pans back to Guilty Spark
343 Guilty Spark: Tell your Chargers to ceace all agression to the Reclaimers, and leave this installation at once."
-Now we see cells deviding as would be seen on a microscope
343 Guilty Spark: "Construct, you are dangerously close to unleashing a force you cannot yet comprehend."
-A forerunner view screen shows a hand of an Elite that is being taken over by Flood, then pans to see both 343 Guilty Spark, and the Unknown Construct.
343 Guilty Spark: "This is most inappropriate."
Unknown Construct: "We follow the path, and I am part of the stone journey that serves... I, we, serve. They will find, then I will be free."
343 Guilty Spark: "Find? Free? Explain yourself."
Unknown Construct: "I know their path, and when they have gone, only I shall remain. And then, free."
343 Guilty Spark: "This is quite unsatisfactory, Construct. Your core shows no inch of understanding the gravity of the situation. I will return later for your proper decommissoning. Well, unless the Flood kills us all first, in which case the point will be moot. Good day, Construct."
-The screen fades out
Nuff said. I think we might be seeing this fellow in Halo 4. VERY interesting.
[Edited on 11.18.2011 9:09 PM PST]