I wrote here, that since my switch to Linux kernel 2.6.32 the ACPI wakeup didn’t work anymore. After a new search through the internet I came across this article mentioning a conflict with the HPET. As a workaround booting with hpet=disable is suggested.
And indeed with this workaround ACPI wakeup works again. Looking at the output of cat /proc/driver/rtc
rtc_time : 11:44:20
rtc_date : 2010-02-17
alrm_time : 07:21:16
alrm_date : ****-**-17
alarm_IRQ : no
alrm_pending : no
24hr : yes
periodic_IRQ : no
update_IRQ : no
HPET_emulated : no
DST_enable : no
periodic_freq : 1024
batt_status : okay
the HPET_emulated line should report no.
Another fix was released with the xorg-server 1.7.5. Since the switch to xorg-server 1.7 I was basically unable to switch from the X11 display running with 1600×1200 resolution to a virtual console. Switching to a virtual console resulted in a dark display complaining about illegal operating parameters. This was particular annoying, when shutting the system down.
As a workaround with earlier xorg-servers I switched X11 resolution to 1280×1024 with “Ctrl + Alt + Keypad -” and then switched to a virtual console. Now the virtual console was operable.
The fix for xorg-server 1.7 was announced in this email. Unfortunately stupid me didn’t think about the xfce4-display-settings utility (I’m a XFCE4 user), then I would have been able to switch resolutions graphically.