Thanks for this plugin, it's great and I've started to switch all my sites to it.
But I just noticed something strange on one of my sites - after installation and setup, one XML sitemap with 13,683 entries was created manually. Under "Build Options" I have the defaults (Include Homepage, Include Articles, Include Pages).
However, the sitemap itself (sitemap.xml) contains only the Homepage, the 25 Pages and the first post 13,657 times! In other words, no other posts (articles) are included, only the latest post, and it's duplicated about 13,657 times in the sitemap.xml ... (I didn't count it manually, but there are no other posts listed).
P.S. I'm running WP 3.1 and Strictly Google Sitemap V1.0.7. and are using most of the plugin defaults, except for having selected "Auto" and "behind the Scenes" build, and adding Yahoo to be pinged.