If you use Open Embedded you will find the toolchain in /path-to-overo-oe/tmp/sysroots/i686-linux/usr/armv7a.
If you want the toolchain on its own without the weight of Open Embedded there are several options.
The toolchain is already in the Ubuntu 11.04 repository.
$ sudo apt-get install gcc-arm-linux-gnueabi
Emdebian provide the toolchain in their Debian repository. Add the following line to your sources.list file.
deb http://www.emdebian.org/debian/ squeeze main
Don't forget to update before the install.
$ apt-get update $ apt-get install gcc-4.4-arm-linux-gnueabi
g++ is available as well.
$ apt-get install gobjc++-4.4-arm-linux-gnueabi
Binaries and source: