What's new ? According to dot.kde.org KDE 4.8 brings many improvements for stability and performance.
A key feature are new Plasma QtQuick components, which brings more eye candy to the end user, and more easy and really quick development.
Another feature is new rendering engine for Dolphin. I can see some animations when changing icon sizes, but more awaited single application mode is not present. At least I can not see any improvement on startup time, which must be very quick if single application pattern is used.
What I like more is inclusion of popular IconTask widget. It has support for Unity API - quicklists, progressbars etc. I found it is very useful and I really missed it in previous versions. If you have installed this plasmoid via AUR, you must remove it first - just in case to avoid misconfiguration.
Newer KDE also has adaptive (per workspace) power management, which is very useful if you use plasma workspaces and actvities. I'm not.
I also can see some more speed in Kwin, but of course I switch back to my compiz cause I dont like KWin at all.
To install KDE 4.8 in ArchLinux just update your system if you have installed it before.
% pacman -Syu
If you have not installed KDE before, here is how to install barebone one:
% spacman -Sy kde-meta-kdebase kdemultimedia-kmix kdesdk-kate kdeplasma-addons-applets-icontasks
If you don't like Oxygen look and feel (like me) you may intall QtCurve, which is by far most advanced theming engine for KDE and Gtk2 for now. See how:
% pacman -S qtcurve-kde4 qtcurve-gtk2
For KDM you have to add it to the DAEMONS sections of yout rc.conf file. Users of ArchBang have to switch to init 3 in their inittab file (which is default in ArchLinux, but not in ArchBang).
Here how my inittab file looks:
# 0 Halt
# 1(S) Single-user
# 2 Not used
# 3 Multi-user
# 4 Not used
# 5 X11
# 6 Reboot
## Only one of the following two lines can be uncommented!
# Boot to console
# Boot to X11
And here is my rc.conf DAEMONS section:
DAEMONS=(dbus networkmanager syslog-ng @laptop-mode @alsa kdm)
That's all. Just reboot (it may be not required, but preferred) and voila.