I call this script trun. I suggest putting it in a directory in your executable path. Make sure it is executable like this:
chmod +x ~/bin/trun
Then you can run commands in a new window by just adding trun before them, like this:
trun tail -f /var/log/system.log
Here's the script. It does some fancy things like pass your arguments, change the title bar, clear the screen to remove shell startup clutter, remove its file when its done. By using a unique file for each new window it can be used to create many windows at the same time.
#!/bin/bash
# make this file executable with chmod +x trun
# create a unique file in /tmp
trun_cmd=`mktemp`
# make it cd back to where we are now
echo "cd `pwd`" >$trun_cmd
# make the title bar contain the command being run
echo 'echo -n -e "\033]0;'$*'\007"' >>$trun_cmd
# clear window
echo clear >>$trun_cmd
# the shell command to execute
echo $* >>$trun_cmd
# make the command remove itself
echo rm $trun_cmd >>$trun_cmd
# make the file executable
chmod +x $trun_cmd
# open it in Terminal to run it in a new Terminal window
open -b com.apple.terminal $trun_cmd