With Facebook's massive initial public stock offering looming, Yahoo has filed a lawsuit accusing the social media powerhouse of patent infringement. Yahoo says Facebook, which is likely to be valued at around $100 billion, pilfered its innovations on a wide array of social-web staples, from personalized advertising to news feeds to messaging. Many critics have dismissed the claim as bogus, noting that Yahoo made a similar move against Google before its IPO. Is this just a "pathetic" last stand for a fading internet pioneer, or does Yahoo have a legitimate case?

Yahoo is making a fool of itself: Pathetic is putting it kindly — these patent claims are "a crock of shit," says venture capitalist Fred Wilson at AVC. Not one of the patents in question is based on a unique idea Yahoo developed on its own. "Pretty much everything" on the web today is based on innovations made "before the commercial web existed." So look out, Yahoo. "Other companies have bogus patents too," and now they now have good reason to sue you right back.
"Yahoo crosses the line"

But you can see why Yahoo is suing: New CEO Scott Thompson needs to restore the company's "self-respect," says Ashlee Vance at Bloomberg Businessweek. His "predecessors did a woeful job of celebrating Yahoo's engineering chops, turning Yahoo into a punchline. It's an image that the company must shake," and clearly, Thompson is intent on reminding us that his company "owns core technology around messaging, displaying ads, and fighting fraud" — and won't simply "roll over and play dead" while rivals make money off those innovations.
"Yahoo's suit against Facebook: A quest for self-respect"

And Facebook isn't entirely innocent: There's some old, "simmering animosity between the two companies," says Om Malik at GigaOm, and it's not all Yahoo's fault. Over several years, Facebook gained hundreds of millions of users by "pillaging Yahoo's email address books." It got so bad that Yahoo tried to block Facebook, only to "back down" when the companies struck a deal in 2009. Now, "for the first time in a long while, Yahoo has management that is willing to mess with Facebook." Whether that's smart is "open to debate."
"Yahoo-Facebook patent fight: more than meets the eye"