<p>I need to do some communications over a serial port in Ruby.  From my research, it appears that there aren't many modern libraries for serial communications and the newest material I can find is from 2006.  Are there any gems that I'm not aware of?</p>

<p>I ultimately need to maintain communications with a serial device attached to USB (I can figure out the port no problem) for back and forth communications like so (somewhat Ruby-esque pseudo code).</p>

<pre><code>def serial_write_read
  if serial.read == "READY"
    serial.write "1"
    until serial.read == "OK"
      serial.write "5"
    end
    return when serial.read == "DONE"
  end
end
</code></pre>

The serial port specification has not changed in forever, I wouldn't worry about how old the libraries are.
I'm assuming you saw
this
article from 2006 about ruby and serial ports
Here's
someone who got the
Ruby-SerialPort
library mentioned there to work on macs this year.
There's also
this old post
from ruby talk, about interfacing to the Win32 Serial API.