Here is a link to a training schedule for those interested in training for 5k-10k and in some cases this would work for those who want to run a faster 1/2 marathon. This schedule presumes that you have been running going into it. This a perfect schedule for those who have just completed a marathon program or a 1/2 marathon program. There is also a 8 week beginner schedule for the new runner/walker .
Below that is a 6 month training plan for a half marathon, this is very beginner friendly. I've set it up date wise for the 2008 Seattle Marathon for those I work with who are planning on participate in that event.
5K - 10K training plan
6 - Month Half Marathon Training Plan(Seattle Half Marathon)