I have updated my tests for both the latest 2.6.38 kernel of natty and the latest 2.6.34 kernel from mainline as suggested, on my Thinkpad T61 laptop.
After login I have sudoed previously, then run:
sudo powertop -d -t 60 > ~/Desktop/powertop_dump-`uname -r`.log
Running on battery, not having started anything but one terminal window after logon.
Both kernels, results below: there is a visible difference still! 15,5W versus 17,9W meaning 3,4 hours versus 2,9 hours = a half an hour of time on battery!

I think both power regressions found by Phoronix at 2.6.35 and 2.6.38 are there.
See http://www.phoronix.com/scan.php?page=article&item=linux_kernel_regress2

2.6.34:
PowerTOP 1.13   (C) 2007 - 2010 Intel Corporation 

Collecting data for 60 seconds 


Cn	          Avg residency
C0 (cpu running)        ( 1,9%)
C0		  0,0ms ( 0,0%)
C1 mwait	  0,0ms ( 0,0%)
C2 mwait	  0,5ms ( 0,4%)
C6 mwait	  6,2ms (97,7%)
P-states (frequencies)
Turbo Mode     0,9%
  2,50 Ghz     0,0%
  1,60 Ghz     0,0%
  1200 Mhz     0,0%
   800 Mhz    99,1%
Wakeups-from-idle per second : 164,1	interval: 60,0s
Power usage (ACPI estimate): 15,5W (3,4 hours) 
Top causes for wakeups:
  29,5% ( 61,0)   [uhci_hcd:usb5, yenta, nvidia] <interrupt>
  24,2% ( 50,0)   [kernel core] hdaps_mousedev_poll (hdaps_mousedev_poll)
  19,3% ( 39,9)   [kernel core] hrtimer_start (tick_sched_timer)
  13,4% ( 27,8)   [kernel scheduler] Load balancing tick
   4,8% (  9,9)   gwibber-service
   2,4% (  5,0)   [ata_piix] <interrupt>
   1,7% (  3,6)   compiz
   1,1% (  2,2)   nautilus
   0,8% (  1,7)   gnome-terminal

2.6.38:
PowerTOP 1.13   (C) 2007 - 2010 Intel Corporation 

Collecting data for 60 seconds 


Cn	          Avg residency
C0 (cpu running)        ( 2,2%)
polling		  0,1ms ( 0,0%)
C1 mwait	  0,0ms ( 0,0%)
C2 mwait	  0,6ms ( 0,7%)
C6 mwait	  4,5ms (97,1%)
P-states (frequencies)
Turbo Mode     0,9%
  2,50 Ghz     0,0%
  2,00 Ghz     0,0%
  1,60 Ghz     0,1%
   800 Mhz    99,0%
Disk accesses:
The application 'gvfsd-metadata' is writing to file 'home-3c698ca6.log' on /dev/sda5
The application 'gvfsd-metadata' is writing to file 'home-3c698ca6.log' on /dev/sda5
The application 'rs:main Q:Reg' is writing to file 'auth.log' on /dev/sda5
The application 'rs:main Q:Reg' is writing to file 'auth.log' on /dev/sda5
The application 'rs:main Q:Reg' is writing to file 'auth.log' on /dev/sda5
The application 'gvfsd-metadata' is writing to file 'home.SF5MWV' on /dev/sda5
The application 'gvfsd-metadata' is writing to file 'home.SF5MWV' on /dev/sda5
Wakeups-from-idle per second : 227,9	interval: 60,0s
Power usage (ACPI estimate): 17,9W (2,9 hours) 
Top causes for wakeups:
  24,9% ( 61,0)   [uhci_hcd:usb5, yenta, nvidia] <interrupt>
  20,4% ( 50,0)   [kernel core] hdaps_mousedev_poll (hdaps_mousedev_poll)
  15,1% ( 36,9)   [extra timer interrupt]
  14,8% ( 36,4)   [kernel core] hrtimer_start (tick_sched_timer)
   7,4% ( 18,2)   compiz
   6,2% ( 15,2)   [kernel scheduler] Load balancing tick
   4,1% ( 10,0)   gwibber-service
   2,2% (  5,5)   kworker/0:0
   1,6% (  4,0)   [ata_piix] <interrupt>
   0,0% (  0,0)D  gvfsd-metadata
   0,0% (  0,0)D  rs:main Q:Reg
   0,9% (  2,3)   nautilus
   0,7% (  1,7)   gnome-terminal