So what is the update all about? Microsoft makes it clear that when you sign into your account, the company will "collect certain information in order to verify your identity, to protect you from malicious account usage, and to protect the efficiency and security of the Microsoft account service". Furthermore, this information may be shared with partner companies you link to.
Take a look at the statement and it appears, at first glance, to be a fairly short document, but there is actually a good deal more text hidden behind the numerous Learn More links.
There's quite a lot to trawl through, but there is one section that is of particular note: "You should not expect any level of privacy concerning your use of the live communication features such as voice chat, video and communications in live-hosted gameplay sessions offered through the Services."
The statement goes on to say: "We may monitor these communications to the extent permitted by law, but we cannot monitor the entire Service and make no attempt to do so. You understand that others can record and use these communications."
Elsewhere, it is pointed out that Xbox Services are supported by advertisements, but a link is provided to the "Personalized ad preferences" page where it is possible to opt out of targeted ads.