Ok, here are some quick fixes:
I. Upgrade from previous Beta4, r121, r1xx ... (assuming U-Boot has already been installed in your Z)
Flashing the new image is now not done in the Sharp Flash ("OK") menu. So you need to do this to install the new release
1) Unzip the new release archive to the root of SD or CF (in my case SD works but not CF); make sure that there are three files - autoboot.sh, kernel.img, rootfs.img
2) Take out AC and the battery. Wait 10 secs.
3) Press the OK button on the keyboard.
4) Put the battery back and plug in AC.
5) Power on the device.
6) It should boot into the Emergency system screen.
7) You'll be asked whether to proceed to install pdaXrom or the emergency system. Press "y" and then [ENTER].

Then you will be in a bash prompt (heading with a hash "#"). Switch to the location where the release files are:
cd /mnt/card (or cd /mnt/cf )
9) Run the installation script by typing
./autoboot.sh .
(the last dot "." is necessary)
10) Then you'll be asked once again whether to install pdaXrom or the emergency system. Again, press "y" and then [ENTER]
11) Flashing will then begin. Just let it do its job. It may take minute or two.
12) After flashing is done, the system will reboot automatically.
13) One new thing you'll notice is: upon first booting you have a choice of logging in as a non-root user. Just make your choice. I choose "n", which means to be root, because things get easier.
14) Go through the fixes in II & III.
II. Fix the card mounting issue (thanks to louigi600 for providing this)You will notice that upon reboot after flashing, both SD and CF are not mounted.
To fix this, edit /etc/fstab. Use your favorite editor to do so.
Open the file, in the lines for /dev/hda1 (for CF) and /dev/mmcblk0p1 (for SD), change
noauto,owner
to
owner
Save the file, exit the editor.
Then the cards will be mounted automatically.
III. Fix the four application keys (Calendar, Address, Mail, Home)Edit /etc/X11R6/kb/[Husky/Akita/whatever-your-Z-is-called]/xmodmap
(Note the following applies to C760/860; C1000/3000/3100/3200 have a different keymap)
First look for "keycode 107" (= the Home key), you will see its mapped to "XF86AudioPrev", pressing it will launch xmms, in addition to power on your Z. Strange (and annoying, too ).
So change it to
keycode 107 = XF86LaunchD
Moreover, add
keycode 67 = XF86LaunchA
keycode 68 = XF86LaunchB
keycode 76 = XF86LaunchC
(XF86LaunchA = Calendar; XF86LaunchB = Address, XF86LaunchC = Mail)
Save the file. (Re)Start X.
The four keys should work now.
The Menu key (XF86Start) doesn't seem to work in Matchbox. In Icewm that can be easily fixed by assigning XF86Start to something (see the "icewm ultimate configuration" thread for example)
That's all for now. This build seems less crazy than the previous ones. Will keep testing it.
Many thanks to all the devs for all the hard work to build. You've come a long way!
Again, please report bugs in the bugtracker (see my signature).