$this->bbcode_second_pass_code('', '
Arch Linux 3.1.9-33-ARCH+ (ttyAMA0)
rpi login:
')
But it does not accept input. I thought perhaps connectivity through one of the lines might be bad, so I double checked that, and it is fine. I also tried swapping rx/tx and that resulted in not even receiving the login prompt. I am downloading the Raspbian distro and plan to try that next.
Update: I got the Raspbian distro downloaded installed and booting. I see a lot more messages on boot up, but it also is not accepting input. Perhaps I will try making another cable.
Update #2: After thinking about it more, I decided to test my cable again, it still checked out. Next, I thought I would check the soldering on the board... I am pretty sure I found the problem. On the back side of the board, there is a bridge of solder from the rx pin (GPIO 15) across the tx lead over to the DNC (do-not-connect) pin. I am going to try to clean it up and see if that fixes it.

Update #3: This will likely be the last edit to this post. I cleaned up the solder and now my Pi is behaving as I expected. It appears the sloppy soldering was indeed the source of the problem.
Now that my serial connection is working, my next question is, how do I get Arch Linux ARM to dump all the kernel messages on boot up? As mentioned above when booting Arch Linux ARM, the first thing I see on the serial port is the login message, but when I boot Raspbian, I see messages from what looks like the entire boot process. I did some searching and looked for differences between the boot config files and the files in /etc. The boot config files are more or less the same. The most promising thing I found was the following line in the Raspbian /etc/inittab file:
$this->bbcode_second_pass_code('', '
T0:23:respawn:/sbin/getty -L ttyAMA0 115200 vt100
')
I added it to the Arch Linux ARM inittab file, but I saw no difference in boot messages when I rebooted. My next guess would be that it is something compiled into the kernel. Does anyone know what I need to change? Thanks.
Update #4: I guess the previous will not be my last update. After a bit more digging it appears that in order to see more kernel messages the "loglevel" variable in /boot/cmdline.txt needs to be changed from 2 to something greater than 2, with a max of 7 (see this https://bbs.archlinux.org/viewtopic.php?id=144847).