tedster - 3:02 am on Sep 16, 2010 (gmt 0) [edited by: tedster at 6:03 pm (utc) on Sep 16, 2010]
Here's a relevant comment from a Google employee on the Adwords Support forum:
If you use both the previous and updated versions of the Keyword Tool to search for keywords, you may notice differences between the tools for statistics on Global Monthly Searches and Local Monthly Searches.
This is because the previous version of the Keyword Tool provides search statistics based on Google.com search traffic AND traffic from search partners, while the updated version of the Keyword Tool provides search statistics based on Google.com traffic only. We've updated these statistics based on user feedback, and hope you find them helpful for keyword selection.
[google.com...] [emphasis added]
[edited by: tedster at 6:03 pm (utc) on Sep 16, 2010]