Per http://yoast.com/articles/wordpress-seo/#stopwords:
"As of version 1.1.6, my WordPress SEO plugin will automatically remove stop words from your slugs once you save a post, so you won’t get those ugly long URL’s when you do a sentence style post title."
The original thread with this issue seemed to have been closed (marked as resolved) due to the release of WordPress SEO 1.1.7:
http://wordpress.org/support/topic/plugin-wordpress-seo-by-yoast-stopwords-functionality-not-working?replies=12#post-4111828
However, I am still running into this issue with the following software versions:
WordPress 3.5.1
WordPress SEO 1.4.7
Example title: AWS VPN Cisco ASA and SLA Monitor
Example slug: aws-vpn-cisco-asa-and-sla-monitor
Example URL: http://virtuallyhyper.com/2013/04/aws-vpn-cisco-asa-and-sla-monitor/
Thanks for the plugin! Any thoughts on this? It seems like many others in the original thread were having the issue as well, even after the update.