According to Runner's World, 75% of their subscribers over the past 4 years have been women and 10 million women across the country identify themselves as regular runners. That's a lot of women runners! Thats why Women's Running Magazine seems to make sense. According to the website, "Women's Running covers all aspects of the running lifestyle, from active beauty needs to training plans".
Women's Running debuts in Jan 2009 as a re-branding of "Her Sports + Fitness", a magazine I've never heard of (probably why its getting rebranded). The website says you'll be able to find it at book retailers like Borders and Barnes & Noble. An annual subscription (with 10 issues) is $19.95 ... but I think I'll pick up an issue next time I see one to check it out before I jump on the bandwagon.
The magazine also has its own blog which (at a scan) has some interesting posts. It looks like its topic driven and the posts are irregular with the most recent dated 12/3, but it's another blog to add to the reading list!