Here's the account from the Darth Plagueis book for anyone who wants to read it. Really great stuff Warning: Spoiler! (Click to show)
They find out about Anakin though Dooku. Palps is talking to him and Dooku let's him know everything about Anakin.
"Qui-Gon returned from Tatooine with a former slave boy. According to the boy’s mother, the boy had no father.”
“A clone?” Palpatine asked uncertainly. “Not a clone,” Dooku said. “Perhaps conceived by the Force. As Qui-Gon believes.” Palpatine’s head snapped back. “You don’t sit on the Council. How do you know this?”
“I have my ways"
Does this have something to do with the prophecy you spoke of?”
“Everything. Qui-Gon believes that the boy—Anakin is his name—stands at the center of a vergence in the Force, and believes further that his finding him was the will of the Force. Blood tests were apparently performed, and the boy’s concentration of midi-chlorians is unprecedented.”
“Do you believe that he is the prophesied one?”
“The Chosen One,” Dooku amended. “No. But Qui-Gon accepts it as fact, and the Council is willing to have him tested.”
“What is known about this Anakin?”
“Very little, except for the fact that he was born into slavery nine years ago and was, until recently, along with his mother, the property of Gardulla the Hutt, then a Toydarian junk dealer.” Dooku smirked. “Also that he won the Boonta Eve Classic Podrace.” Palpatine had stopped listening. Nine years old … Conceived by the Force … Is it possible … His thoughts rewound at frantic speed: to the landing platform on which he and Valorum had welcomed Amidala and her group. Actually not Amidala, but one of her look-alikes. But the sandy-haired boy, this Anakin, swathed in filthy clothing, had been there, along with a Gungan and the two Jedi. Anakin had spent the night in a tiny room in his apartment suite. And I sensed nothing about him.
“Qui-Gon is rash,”Dooku was saying. “Despite his fixation with the living Force, he demonstrates his own contradictions by being a true believer in the prophecy—a foretelling more in line with the unifying Force.”
“Nine years old,”Palpatine said when he could. “Surely too old to be trained.”
“If the Council shows any sense.”
“And what will become of the boy then?”
Dooku’s shoulders heaved.
“Though no longer a slave, he will probably be sent to rejoin his mother on Tatooine.”
“I understand your disillusionment,”Palpatine said.
Dooku shook his head. “I haven’t told you all of it. As if the announcement of having found the Chosen One wasn’t enough, Qui-Gon discovered that the Trade Federation may have had the help of powerful allies in planning and executing the blockade of Naboo.”
Palpatine sat straighter in his chair. “What allies?”
“On Tatooine, Qui-Gon dueled with an assassin who is well trained in the Jedi arts. But he dismissed the idea that the assassin is some rogue Jedi. He is convinced that the warrior is a Sith.”
Ignoring the reactions of apprehensive residents and wary security personnel, Plagueis hastened along a plush corridor in 500 Republica toward Palpatine’s suite of crimson rooms. He had planned to be at the Senate Building to hear Amidala’s call for a vote of no-confidence in Valorum, which would strike the first death knell for the Republic. At the last moment, however, Palpatine had contacted him to recount a conversation he had had with Dooku. The fact that Qui-Gon Jinn had identified Maul as a Sith was to be expected; but Dooku’s news about a human boy at the center of a vergence of the Force had come as a shock.
More, Qui-Gon saw the boy as the Jedi’s prophesied Chosen One! He had to see this Anakin Skywalker for himself; had to sense him for himself. He had to know if the Force had struck back again, nine years earlier, by conceiving a human being to restore balance to the galaxy. Plagueis came to a halt at the entry to Palpatine’s apartment. Eventually one of Queen Amidala’s near-identical handmaidens came to the door, a vision in a dark cowled robe. Her eyes fixed on the breath mask. “I’m sorry, sir,”she said, “Senator Palpatine is not here.”
“I know,”Plagueis said. “I’m here to speak with a guest of the Senator. A young human boy.”
Her eyes remained glued on the mask. “I’m not permitted—”
Damask motioned swiftly with his left hand, compelling her to answer him. “You have my permission to speak.”
“I have your permission,”she said in a distracted voice. “Now where is the boy?”
“Anakin, you mean.”
“Anakin, yes,”he said in a rush. “He’s the one. Fetch him—now!”
“You just missed him, sir,”the handmaiden said. Plagueis peered past her into Palpatine’s suite.
“Missed him?”He straightened in anger. “Where is he?”
“Jedi Master Qui-Gon Jinn came to collect him, sir. I suspect that you can find him at the Jedi Temple.”
Plagueis fell back a step, his thoughts reeling. There was still a chance that the Council would decide that Anakin was too old to be trained as a Jedi. That way, assuming he was returned to Tatooine …But if not … If Qui-Gon managed to sway the Council Masters, and they reneged on their own dictates …Plagueis ran a hand over his forehead. Are we undone? he thought. Have you undone us?