Even Matt's allegation is softened by "I believe" here: there appears to be nothing that conclusively indicates Bing is solely targeting Google. For example, the observed behaviour could be a side-effect of a generic algorithm to extract and associate search queries with a user's click stream, which is only a minor variant of what Google itself does with its own toolbar.

If the case described above were true, then all Google has done here is to make inconclusive accusations and use the occasion to highlight its own dominance over search.

It seems to me this is just a cheap and slightly seedy PR stunt.