In what has become a typical negotiating tactic in patent cases, salesforce.com has answered Microsoft's charge of patent infringement with a countersuit.

For amusement's sake, it's using Microsoft's old nemesis David Boies for the job. He's the hired gun the Justice Department brought in to argue its antitrust case against Redmond.

Oracle just hired Boies too. It wants him to win in its great billion-dollar IP theft suit against SAP and its now-defunct TomorrowNow maintenance subsidiary.

Not winning SCO's litigation against Novell and IBM seems to have worked wonders for Boies and his firm. He didn't win the presidency for Al Gore either and the Microsoft break-up order handed down at trial didn't stick.

Salesforce CEO Marc Benioff famously called Microsoft a "patent troll" and "alley thugs" after it filed one of its very rare infringement suits against him in May, alleging that his company's menus, toolbars and UIs tread on nine of its patents.

Salesforce in return says Microsoft infringes five of its patents: a multi-level cache management patent in Windows Server AppFabric, Azure's app provisioner; an error handling patent in Windows 7 and Windows Server 2008 R2; a web-based work sharing patent in SharePoint; a Java object cache server database patent in .NET, for example, in ASP.NET Web Services; and a provisioning patent in Windows Live's Delegated Authentication System apparently meaning to implicate HotMail and SkyDrive storage.

Microsoft's deputy general counsel Horacio Gutierrez issued a statement saying, "We remain confident about our position and will continue to press ahead with the complaint we initiated.

Analyst Rob Enderle has said Microsoft is suing on core patents, making an example of salesforce and has to win.

Microsoft is suing salesforce in district court in Seattle and using Sidley Austin, a winner of many an IP case. Salesforce is suing Microsoft in Delaware.

Both are asking for injunctions and treble damages.