In a recent update to AdWords, Google has added two columns of search volume data to their keyword tool.  These two columns are previous months total searches and average months toatl searches.  According to the Inside AdWords Blog, search volume data can be useful to you in several ways, including:

• Account structure: You may want to create a new ad group around high-traffic keywords that you find particularly relevant. Closely target ad text and a specific landing page to the small, narrowly-focused set of similar keywords you’ve found through the Keyword Tool.
• Budget planning: See how much traffic is available to your keywords so you can better plan your budget.
• Keyword choice: Search for and select the relevant keywords most likely to return quality leads within your budget.

I do not believe that these search volume numbers are broken down to a geo-targeted level if you are creating a local or regional campaign, however, I have found this tool to be VERY valuable in creating new campaigns and ad groups and is a great complement to the current advertiser competition metric.