[Boromir88]

Yes, but that would have exposed that information to Saruman too. Why give him the benefit of his power?~Raynor

I've never heard that before, but it certainly makes sense to me. If Sauron's number 1 concern was getting the Ring back, I would guess his second concern was others falling on information about the Ring...especially someone like Saruman. So, are you arguing that 'dainty' and 'it' are not necessarily referring to Pippin himself, but information about the Ring that Pippin has and then could reveal to Saruman (or others)...which would cause just a little doubt and fear in Sauron? If so, that's an interesting spin on things and never heard it before (that's a good thing) and I can see it making sense.

As you say, Sauron would not want others to get any information about the Ring. If he believes Pippin has this information he will not only be useful for information, but Sauron would want him immediately so he didn't give any away to Saruman (or anyone else for that matter). I'll say if (because I still think he believed Pippin had the ring...which I will get to shortly), but if Sauron believed Pippin didn't have the Ring than it would still make sense.

Sauron began getting worried about Saruman and was wondering what he was sticking his hands in. If Sauron believed Pippin didn't have the Ring he would have to figure Saruman would figure this out (if he hadn't already). Then Saruman would begin to question Pippin the whereabouts of the Ring and this would fall under great concern from Sauron. So, I think that's a reasonable explanation, that Sauron didn't just want information from Pippin, he wanted to make sure that information didn't get into anyone's hands but his own.

Precisely. Given how important finding the Ring was to Sauron, don't you think that, if he did not believe this Hobbit to be the Ringbearer, he would have asked straight away about the Ring?~Sauce

Good point...from what Gandalf says:

"You have been saved, and all your friends too, mainly by good fortune, as it is called. You cannot count on it a second time. If he had questioned you, then and there, almost certainly you would have told all that you know, to the ruin of us all. But, he was too eager. He did not want information only: he wanted you, quickly, so that he could deal with you in the Dark Tower, slowly."

This should support Raynor's valid point that it really wasn't a matter that Pippin resisted telling Sauron information...but it was a matter of time. Pippin had escaped just in time, but there is certainly no doubt in Gandalf (nor me) had Pippin been questioned about the Ring he would have spilled the beans.

Though I think that Gandalf believed Sauron thought Pippin had the Ring and he was going to use this to their advantage. As he puts it:

'Not yet,' said Gandalf. 'There remains a short while of doubt, which we must use. The Enemy, it is clear, thought that the Stone was in Orthanc - why should he not? And that therefore the hobbit was captive there, driven to look in the glass for his torment by Saruman.'

I think that sentence bolded above is interesting. At least Gandalf believes Sauron is facing some doubt right now (and I would agree with Gandalf here). Sauron was in doubt, about what? The ring? I think so, we know for sure that Sauron believed (though it wasn't true) that the stone was in Orthanc and Pippin was captive there...he did not doubt that he was just wrong. So, what is it that Gandalf believed Sauron did doubt? It would either be, does this hobbit have my ring? or as Raynor argues thinking that others will come across important information on where it is, (which would also fill him with doubt) Pippin got away at the 'fortunate' time as Sauron's head must be spinning after this point. And I think he would even be filled with more doubt once Aragorn reveals himself in the palantir. This causes Sauron to attack at Gondor sooner than he had hoped for, before his full strength was mustered.