The icon shows the battery as depleted but the tooltip says 49% remaining. Here's a link to an image demonstrating the issue:
http://people.ubuntu.com/~mnuzum/tmp/batterystatus.png

Linux - Ubuntu dapper 6.06
Linux matts-laptop 2.6.15-26-686 #1 SMP PREEMPT Mon Jul 17 20:14:14 UTC 2006 i686 GNU/Linux
Toshiba Satelite A105 laptop

gnome power management installed via package gnome-power-manager  2.14.3-0ubuntu11 

At the time of writing this, my battery has dropped to 40%. Here are the details:
/proc/acpi/battery/BAT0/alarm
alarm:                   unsupported
/proc/acpi/battery/BAT0/info
present:                 yes
design capacity:         3900 mAh
last full capacity:      3900 mAh
battery technology:      rechargeable
design voltage:          15000 mV
design capacity warning: 0 mAh
design capacity low:     0 mAh
capacity granularity 1:  0 mAh
capacity granularity 2:  3900 mAh
model number:            PA3399U-2BAS/BRS
serial number:           02E2
battery type:            Li-ion
OEM info:
/proc/acpi/battery/BAT0/state
present:                 yes
capacity state:          ok
charging state:          discharging
present rate:            1542 mA
remaining capacity:      1570 mAh
present voltage:         15000 mV


$ gconftool-2 -R /apps/gnome-power-manager
 check_type_cpu = true
 can_hibernate = true
 ac_sleep_display = 1800
 battery_brightness = 70
 action_button_power = interactive
 lock_on_hibernate = true
 action_ac_button_lid = suspend
 battery_sleep_computer = 1200
 lock_on_suspend = true
 dim_on_idle = true
 lock_on_blank_screen = true
 notify_hal_error = true
 ac_brightness = 100
 display_icon_policy = always
 use_time_for_policy = true
 notify_fully_charged = true
 policy_suppression_timeout = 5
 action_button_suspend = nothing
 action_sleep_type = nothing
 notify_ac_adapter = true
 ac_sleep_computer = 0
 battery_sleep_display = 300
 action_battery_button_lid = blank
 can_suspend = true
 action_button_hibernate = hibernate
 action_battery_critical = shutdown
 suppress_suspend_warning = false
 check_type_net = true
 lock_use_screensaver_settings = false