No one's launched a product or sent in the lawyers just yet, but it looks like Yahoo is on Google's tail in terms of instant search and might trip up its rival with a legal objection. Shashi Seth, Senior Vice President of Yahoo Search Products, has indicated that Google Instant infringes on perhaps five patents Yahoo holds. Let's start with the legal issue. Cade Metz recently interviewed Seth and reported this afternoon, "Seth reiterated that Yahoo!