Sony is slowly but surely rolling out lollipop to its Xperia Z family of devices. Most of the models within the Xperia Z3 and Xperia Z2 series have already been updated to at least Android 5.0.2, with exception of the T-Mobile model Xperia Z3 which just recently entered into the T-Mobile testing phase, the last stage before finally being rolled out to users. As of today it appears Sony has begun sending out the software updates for Android 5.0 lollipop to a few more phones in the Xperia Z line, this time being the Xperia Z1, Xperia Z1 compact and Xperia Z Ultra.
Sony's official blog post about the software updates says that it's started rolling out the software today which means some users will begin to receive the updates today, but not all users. Software updates tend to happen in staged rollouts, so users can expect the lollipop update to hit sometime between now and likely the middle of next week. Sony doesn't mention which models exactly of all three listed devices are getting the upgraded software, they simply mention the "Xperia Z1 series" so it's probably safe to assume that various different models of the phone are going to be getting the update. Sony also lists that timing may vary by market and carrier, so the update could be hitting some devices here in the U.S. for example, but be a week out in some other regions.
According to Xperia Blog, the update has hit Xperia Z1 devices in Canada who are on the Telus network, with those users being the only reports so far having mentioned getting email notifications about the software update from Sony. The update itself will take up about 1.2GB of storage space, and according to the changelog Xperia Z1 devices will see plenty of changes including Material Design UI changes, an LED light which stays lit across all sound modes, improved performance of data transfer from internal to external storage, improved messaging in Ultra Stamina mode, and of course the close all button has come back for these devices as well, something that unfortunately disappeared with Android Lollipop.