That's precise if you want to have valid code, but the accuracy is off. Google hasn't ever required valid code and hasn't changed recently. Sure, it'd be nice if everyone were to code everything properly, but I've seen plenty of sites that don't do it right that are listed just fine in the SERPs.
This page:
http://wildleg.com/?c=25&st=p&d=DESC is indexed, and I never got around to changing that & to valid code. It's even ranked at various times for keywords on the page, which wasn't ever planned. It was a nice bonus, though.
On the Google Sitemap program, that's a little different - you want to do that correctly. But their bots aren't as picky as their Sitemap program. Just think of how many pages they'd exclude if they required that links be valid - and with Yahoo already showing an index well over double what Google claims, they don't want to exclude that many pages.
Brian.