Even if you don’t have an iPhone 4S (or a jailbroken iOS device running Spire), you know what Siri is. It’s the voice-activated “killer app” for the iPhone 4S, introduced in October. It’s the focus of pretty much every ad for the iPhone 4S you’ve ever seen (including some recent ones with celebrities).

Siri is also, however, a subject of some controversy. While most iPhone users like it, others hate it. Some of those even claim that Apple’s ads are deceptive and are suing Apple for false advertising.

Whatever else Siri may be, though, there’s one thing that Apple has emphasized from the beginning: as cool as Siri can be when it’s working properly (like in Apple’s ads), the feature is still in beta. Unfortunately, that means that Siri won’t always work like it’s supposed to.

Speaking to Walt Mossberg and Kara Swisher last night at AllThingsD’s D10 Conference, Apple CEO Tim Cook acknowledged Siri’s problems, and promised that the personal assistant software would be getting some big improvements in the future.

Mossberg pointed out that “when Siri works, it works really well, it’s kinda like magic.” He went on to say, though, that “a lot of times it actually doesn’t work, and that’s not what a lot of people have come to think about Apple products.” He wondered whether Siri was up to Apple’s standards. Cook replied by pointing out Siri’s popularity with users of the iPhone 4S, which is “the most popular selling phone in the world.” Nevertheless, he acknowledged that “there’s more that it can do.” He said that Apple has “a lot of people working on this,” that they had “some cool ideas about what Siri can do, and that “I think you’ll be really pleased with some of the things that you’ll see in the coming months on this.”

Swisher then asked Cook whether voice interaction would be critical to the phone industry moving forward. Cook replied that “Siri’s proven to us that people want to relate to the phone in a different way.” Siri, he said, represents the first real innovation in mobile technology interface since the touchscreen (which, of course, was brought into the mainstream by Apple with the original iPhone in 2007). Cook said that what makes Siri amazing is its ability to understand the context and intent of what’s being said, “not just voice recognition, voice recognition’s been around for a long time.” Siri’s best feature, Cook said, “is that she has a personality, she becomes many people’s best friend.” When Mossberg jokingly asked if that wasn’t actually kind of sad, Cook replied “hey, I’m not a judge.”

Getting more serious again, Cook said that Siri “is something that people dreamed of for years, and it’s here.” He went on to say that “yes, it can be broader and so forth, but we see unbelievable potential here.” He concluded that “you’re going to be really happy with where this is going, we’re doubling down on it.”

Later in the evening, Cook was asked about how Apple names new products, specifically the new iPad (as opposed to the iPad 3). He noted that the iPad naming represents a return to what Apple usually does with its products – e.g., the MacBook Air, iMac, and iPod. He also briefly touched on iPhone naming conventions, pointing out that the S in iPhone 3GS stood for “speed.” He then confirmed what most have long suspected: the S in the iPhone 4S name stands for “Siri.”

Just as with Facebook integration in iOS, Cook carefully avoided giving any hint of when we might expect the improvements to Siri that he’s talking about. With the WWDC 2012 conference – and the probable unveiling of iOS 6 during Apple’s keynote – just around the corner, though, it’s a fair bet that at least some of these improvements will be coming very soon.

You can see the video of Cook’s remarks about Siri below: