AV Watch has done a review of the new Z-Series which is available for purchase in Japan. You can find the translated version of the post from AV Watch here. It appears that the new Z ships with NC headphones (MDR-NWNC33) and a WM-post to USB cable for transfers. The 4.3 inch screen has a resolution of 480x800 which is said to offer a good viewing experience. Supported video formats are MPEG-4 AVC/H.264 (.Mp4, .M4v), MPEG-4 (. Mp4,. M4v) and WMV. The new Z does feature a micro HDMI port which is handy when connecting to a TV but it appears that AV Watch had some issues with this.
Applications from the Android market will work with no problems and with a NVIDIA Tegra 2 1GHz CPU and memory at 512MB, the new Z should have no issues with Tegra games.
The new Z is more expensive than the equivalent Ipod touch but it does feature a larger screen, faster cpu, noise cancellation and of course Android instead of iOS. The main competition may actually come from Sony itself, the PlayStation Vita with its gorgeous 5-inch 16:9 OLED display with a resolution of 960 x 544.
So should one wait for the new Z-Series to hit your local area? At this moment it is not looking too enticing for me personally, since my X-Series provides me with plenty of storage and noise cancellation and I have my phone for everything else. And if you like playing games on a mobile device, I would definitely wait for the PlayStation Vita.