Recently I threw up a post on Tribble Ad Agency regarding a fairly severe problem showing up in Bing and how the problem will be magnified when Yahoo adopts Bing Results.
For URLs that include ampersands (typically used between sets of dynamic attributes), substitute the equivalent escape code & amp ; for the single ampersand character (&) to enable the page to pass HTML validation checks (as in http://www.mysite.com/default.aspx?var=1& amp ;var=2)
Microsoft published the above on the official Bing blog… meaning Microsoft doesn’t accept & by itself in the URL.
The problem stems (as noted on Tribble) with Microsoft’s refusal to accept web standards. They claimed that they are doing it to be compliant, but this is as compliant as IE6.
If you run a dynamically generated site, and see that you are using the & variable in the URL, the chances are that the reason none of your content is being indexed is due to Microsoft refusing to spider content with that url structure.
It’s a bad deal people, Microsoft should comply with web standards… not another round of IE6.