I got a big problem i installed u-boot 13 or like that called.... and i cannot go into maemo the screen is almost black and the letters are showed up only a bit and a little pinguin upper right can i do anything to remove uboot? i want to come back to maemo but is hard i guess
pls help me some1 tnks in advance! :-/

you need to stop the boot process by pressing a key during the boot and type "run noloboot" without the quotes.

i had the same problem.... only happens when you install uboot when you have power kernel installed. It doesn;t matter which version of uboot.... even the power kernel edition caused my phone to stop booting.

Flash the firmware to fix it. http://wiki.maemo.org/Flashing "Updating and Flashing your device". You only need to flash the rootfs, so be sure to use the -F and -f -R commands