[wp-hackers] Permalink problems

[RePost]

I've recently moved my site to WordPress, mainly to take advantage of 
the "friendly urls" format.

My new sitemap looks pretty good, but none of the new urls have appeared 
in Google, so I can't measure the success of my transition from one blog 
format to another.

However, I have noticed that the Web Crawl in Google Webmaster Tools 
returns thousands of 404 errors.

Here's the concern: Many of those 404 errors are urls that append 
WordPress default urls (?p=) to WordPress-friendly urls.

Those urls appear in this format:
http://www.mysite.com/2006/07/12/here-is-my-story/?p=18

I would expect the WordPress permalink structure to prevent these sorts 
of errors. Is there anything I can do on my end to prevent them?

Thanks.