Once installed, fully upgrade your system to the latest packages and this might even pull in a new kernel. Then reboot and try to establish a WLAN connection... At least, I failed. :-( There seems to be a an upstream bug in Lucid's kernel which prevents WPA protected WLAN connections to work properly. The solution seems to be installing the latest Ralink RT2860 WLAN driver. I found this workaround at launchpad published by killerbee - thanks for that! (Have a look at post #25 of the bugreport.) So, I will more or less just sum up his advice here.
As installing a new driver means compiling a kernel module, we need to install the following requirement:
# sudo apt-get install build-essential
Next, I recommend to add yourself to the "src" group. (This step is optional, but if you follow this guide to the letter it's mandatory ;-) ):
# sudo usermod -aG src <USERNAME>
Then logout and in again and download the latest Ralink driver (by the time of writing version 184.108.40.206) for RT2860 from their website (should be the one called "RT2860PCI/mPCI/CB/PCIe(RT2760/RT2790/RT2860/RT2890)"). Once downloaded extract that archive within /usr/src (thats why you need to be in the "src" group):
# cd /usr/src
# tar xvf /path/to/2010_01_29_RT2860_Linux_STA_v220.127.116.11.tar.bz2
Now we need to edit some files:
Line 11: change "HAS_WPA_SUPPLICANT=n" to "HAS_WPA_SUPPLICANT=y"
Line 14: change "HAS_NATIVE_WPA_SUPPLICANT_SUPPORT=n" to "HAS_NATIVE_WPA_SUPPLICANT_SUPPORT=y"
Line 2416: change "WPA_MIX_PAIR_CIPHER FlexibleCipher = MIX_CIPHER_NOTUSE;" to "WPA_MIX_PAIR_CIPHER FlexibleCipher = WPA_TKIPAES_WPA2_TKIPAES;"
Once done, change to the directory of the extracted driver archive and start the compile process:
# cd /usr/src/2010_01_29_RT2860_Linux_STA_v18.104.22.168(don't need to root privileges!!)
# sudo make install
# make clean
Now unload the old module and load the new one:
# sudo ifconfig wlan0 down(just to be on the safe side, don't know if necessary)
# sudo rmmod rt2860sta
# sudo mv /lib/modules/`uname -r`/kernel/drivers/staging/rt2860/rt2860sta.ko /lib/modules/`uname -r`/kernel/drivers/staging/rt2860/rt2860sta.ko_bak
# sudo depmod -a
# sudo modprobe rt2860sta
# sudo ifconfig ra0 up
(Notice: with the new driver the interface is now called "ra0")
This should leave you with a working WLAN which can be configured easily via the network-manager applet.
Please remember: you need to compile the driver again with each kernel update!!!
Again thanks to killerbee, all credits go to him!