I got a 5810T a few days ago, and this thread has been really helpful so far. I upgraded to Karmic shortly after getting Ubuntu installed. So far, I've experienced a few rather major issues
1) Screen tearing issue during video. Karmic fixed this.
2) Cannot change brightness. Like many others, it seems, I cannot adjust the backlight brightness. I haven't been able to get any of the suggested fixes that I've seen to work. The Fn+arrow keys cause Gnome's slider to change, but the actual brightness doesn't. When I try xrandr, I get
I did a bit of searching, and it seems that LVDS is really the only output option that'd make sense for a laptop, so I'm not sure what's going on there. I'm not familiar enough with X or how the screen works in linux to know what to do from there.
> xrandr --output LVDS --set BACKLIGHT_CONTROL native
X Error of failed request: BadRROutput (invalid Output parameter)
Major opcode of failed request: 149 (RANDR)
Minor opcode of failed request: 15 (RRGetOutputProperty)
Serial number of failed request: 30
Current serial number in output stream: 30
3) Resuming from suspend is fairly broken. I can get logged back in after I suspend, but the video is somewhat garbled. The top bar on every menu (the one with minimize, maximize, etc.) is missing, and some of Gnome's menus are covered in lines. Also, any new window I attempt to open isn't visible. Logging out/in seems to fix this issue. I have a sneaking suspicion that the laptop's lack of dedicated video memory and the way that suspend is restoring memory has something to do with this, but I don't know enough to go from there.
All in all, it's decent enough so far, but I am eagerly awaiting the release version of karmic, which will hopefully stabilize the experience. If I can get the brightness and suspend issues fixed, I'll be quite a bit happier.
If anyone has any ideas how to correct my two outstanding issues, let me know. Thanks
edit: I forget to include a couple of other minor bugs I've seen. I've noticed others have mentioned these, as well. The touchpad enable/disable button will disable the touchpad, but when I try to re-enable it, nothing happens. The same goes for the wifi enable/disable button.