After the reports about power consumption regressions with Ubuntu 11.04 I had to measure it myself.
The hardware is a Laptop from 2007:
Dell Latitude D830 T7300 (2*2Ghz), 4GB RAM, 120 GB Intel SSD
I booted different versions of Ubuntu from CD to the GNOME desktop and let the system settle down, meaning that i waited until the CD drive stopped spinning and the CPU fan was off. With the display brightness set to low it was possible to measure the following numbers on the 230V outlet:Ubuntu 8.04 21.3W
Ubuntu 10.04 21.1W
Ubuntu 10.10 21.1W
Ubuntu 11.04 22.8W
So there is indeed a slight regression.
The power usage stayed in the 11.04 case the same even when I killed gdm (and with it X and GNOME).
The display is btw. really a power hog, for 8.04 i measured 27.1W with display to max brightness and 15.3 with the display off.
