There are now quite a few, and which one(s) are most appropriate, depends on your level of experience and area of interest.
<linux-arm@lists.arm.linux.org.uk>. This is the main ARMLinux list which covers ARMLinux topics not specific to and of the other mailing lists. This covers all architectures that ARMLinux is used on (Desktops, PDAs, development boards etc), so much of the discussion is not specifically related to your machine. Users who have ceased to be newbies will find this of interest. To subscribe send "subscribe" (in the body of the message) to <linux-arm-request@lists.arm.linux.org.uk>, or use the web interface at:http://www.arm.linux.org.uk/armlinux/mailinglists.shtml.
<linux-arm-kernel@lists.arm.linux.org.uk> is for kernel-related discussions, generally of a technical nature. This normally covers the kernel, related tools and new hardware. If you are a Linux beginner you won't understand a word of what goes on here :-) This is the place for those interested in the grubby stuff. To subscribe send "subscribe" (in the body of the message) to <linux-arm-kernel-request@lists.arm.linux.org.uk>.
<linux-arm-announce@lists.arm.linux.org.uk> is a moderated low-traffic list for announcements relevant to ARMLinux. To subscribe send "subscribe" (in the body of the message) to <linux-arm-announce-request@lists.arm.linux.org.uk>.
<ARMLinux-toolchain@lists.armlinux.org>This list serves mainly as a place for developers to discuss any aspect of the GNU development toolchain on the ARM architecture (including other operating systems). It's also a diagnostic forum to an extent, if you're having problems. http://www.armlinux.org/cgi-bin/mailman/listinfo/armlinux-toolchain and fill in the form. An archive of submissions to this group is also available from http://www.armlinux.org/pipermail/armlinux-toolchain/
There is a mailing list specifically for people new to ARMLinux, where you are positively encouraged to ask stupid questions. This is aimed at users as opposed to developers, particularly RISC OS machine users and PDA users ,and is at <ARMLinux-newbie@lists.armlinux.org>. This is not the place to ask about toolchains, the kernel, or any development-type questions. This is the place for installation problems, and questions about software that just crashes or doesn't seem to work right. We recommend that all users join this list so that the community can help each other out and compare notes. An archive of submissions to this group is also available from http://www.armlinux.org/pipermail/armlinux-newbie/.
If you are using, or working on, the Debian ARM distribution then <debian-arm@lists.debian.org> is the place to talk to other users and developers about any ARM-specific issues. Debian has loads of maiing lists for other aspects of the distribution.
<emdebian-discuss@lists.sourceforge.net> is a project to make Debian work on small embedded systems and PDAs. It supplies a very good Toolchain and experimental software (CML2+OS)to generate small installations and kernels from the huge Debian archve. It needs some more active developers - join this list if you think you can help or are interested in the design process.
<lart@lart.tudelft.nl> is the place for all tings LARTy. All LART users should be subscribed here. Its the place to get hardware or software help and discuss the possibilities of your LART.
<linux-7110@sourceforge.net> is concerned with the Psion 5/5mx/7 port of ARMLinux. This is a list both for developers and users. Information for the 5mx has recently been obtained from Psion so the list has been revitalised with the new porting activity.
<sa1100-linux@pa.dec.com> is for those who are interested in StrongARM-specific issues - primarily kernel development.
The iPAQ has proved a very popular ARM/PDA development platform due to Compaq's support. There is an active community working on distributions and the hardware on this list: <ipaq@handhelds.org>. Handhelds.org also has other lists, not necessarily specifc to ARM.