After Vito has been transferred home, the women and children (including Carlo ) have to leave the room. Then Tom starts talking: "Since McCluskey's killing, the police have been cracking down on most of our operations"
This line implies that Vito knows already that the Corleones have killed a police captain.
Then: "It was Michael who killed Sollozzo." So Vito knows that Sollozzo has been killed. But he doesn't know who killed him.

I can't really believe that Tom or someone else had delivered Vito in the hospital the disturbing news they have killed McCluskey without having raised the question who did it.

Thoughts?

The Don could have been reading the newspapers, had the papers read to him, picked up on discussions about the McCluskey-Sollozzo murders from his soldiers assigned to guard him at the hospital or even had a quick visit from Clemenza ("You won't see McCluskey no more")

Anyone operating at the Don's level would not be too concerned with the details of who actually carried out a piece of work, especially while they are recuperating from multiple gunshot wounds. Also if any of Vito's subordinates had earlier confirmed that that the Family did the job on the Turk and the cop, they probably would have been prudent enough to let Vito's personal family (Tom and Sonny) discuss Michael's role.

Why be the bearer of bad news if you don't have to be..

I'm with Lilo here, plus an additional point:
Vito certainly had to know both Sol and Mac were dead. But he probably didn't know that Michael did it. He'd have figured that Sonny, the hothead, arranged both murders. I'm guessing that Vito figured (to himself) that if he hadn't been so badly wounded and were able to be in charge, he'd have figured a way to exact revenge on Tat and Sol without killing Mac--thereby avoiding the police crackdown that turned the other families against the Corleones. But he never dreamed it'd be Michael.

Should he have? Quite a few people here put the beginning of Michael's turn toward the Mafia to the hospital scene when he says, "I'm with you now, Pop." Those of us who believe that think that Michael meant "with you" as in "I'm through keeping the Family at arms-length--I'me with you." Vito, in his drugged state, probably thought he meant that he was physically with Vito--nothing more.

Danito, your post raises a subtle point:
Tom treats the killingof McCluskey in an offhand, matter-of-fact way: "Since the killing of McCluskey..." But he bears down on It was Michael who killed Sollozzo." Well, Michael killed both of them. Was the killing of Sollozzo more important or significant than the killing of McCluskey? He should have said, "Michael killed both of them."

Well, Vito would have recognized the name Sollozzo, but maybe not the name McCluskey since his name only came up after Vito was shot.

This is very interesting. Sollozzo was the one who ordered the hit on The Don's life, right? I think Tom only mentioned that Michael killed Sollozzo for Vito to realize his one son who wanted nothing to do with the crime family finally joined them. After all, he's the one who planned and seeked revenge for the attempted hit on the Godfather, that should mean a lot for Vito. To me, I view the McCluskey-Sollozzo hit as Michael making his bones, sort of like an induction into the CRIME family.

While watching GF last night I noticed that Tom mentioned McCluskey first. When he mentioned only Sollozzo, it could have been just one of those things.