"Hey Siri" support and possibly wireless charging case alongside AirPower charging mat.
AirPods and AirPower: Everything We Know
Apple Tweaks British and Australian Speaking Voices for Siri on HomePod
The change appears to be very subtle. MacRumors readers described the Australian Female and British Male voices as "more natural" and "much clearer," and similar reports have emerged about other voices. Although there are many different descriptions for each voice, the consensus appears to be that the tweaks make Siri sound more human-like.
HomePod users can choose any Siri voice no matter the region they are located in, but as of now the vast majority of these reports appear to be located in the same regions as the voice they represent. This may be the beginning of a wider rollout, but that's still unclear at this point.
Twitter user @callumjcoe recorded the difference between the current iteration of the Australian Female voice (on an iPad) and the updated voice (on HomePod). Of course, distortion and muddled sound quality from a recording don't provide a perfect example, but there is a slight change between the two heard in the video, which is likely much more pronounced in person.
In early 2018, Siri creator, co-founder, and former board member Norman Winarsky talked about the origins of Siri and the company's intentions for the assistant before Apple acquired it. According to the co-founder, Siri was originally meant to be incredibly intelligent in just a few key areas -- travel and entertainment -- and then "gradually extend to related areas" once it mastered each. Apple's acquisition pivoted Siri to an all-encompassing life assistant, and Winarsky said that this decision has likely led Apple to search "for a level of perfection they can't get."
Although unconfirmed, the new voice changes to Siri may be Apple's latest attempt to make the voice assistant more personable and easy to talk to, in the wake of ongoing user complaints. If the changes roll out to other regions, we'll update this article.
(Thanks Sebastian, Robert, and Jared!)