Multiple clients sites were de-indexed from yahoo/bing – what is going on?


In the last few days I have had multiple client sites de-indexed from yahoo/bing and there seems to be no rhyme or reason to it. Some sites were done completely white hat and others were black hat sites with completely different themes, owners and linking strategies done. Has anyone else had their site de-indexed from yahoo/bing recently? If so please post the details here so we can figure out what is going on.