I (try to) read a lot of screenwriting blogs. You should, too. I have nearly a dozen queued up in my RSS reader which I scan daily for interesting articles.
Emily Blake recently wrote a good post about log lines. She summed it up with this sentence: “People always make the same mistake. They give the setup, not the plot.”
I too see this same mistake. Your log line should be about your main “A” story, in other words what happens in your second act. The log line isn’t an interesting tag line that sets your story up, it’s a short quick summation of your story.
To read the whole post go here: http://bambookillers.blogspot.com/2012/07/how-to-write-better-logline.html.
You really should check it out. It’s short and very informative.
You might consider following her blog regularly. She recently signed with a top agent and manager and has been blogging about her adventures as she tries to clear the last few hurdles and become a professional screenwriter.