But efforts to build useful computerized assistants have consistently ended in failure, including some of the Valley’s largest “craters” — ambitious undertakings ending as spectacular flameouts. The failures include General Magic, originally backed by Mr. Sculley, E-speak by Hewlett-Packard and Hailstorm by Microsoft.  A Pentagon research project and two Silicon Valley start-up companies are about to try again.  SRI International, a research group in Menlo Park, Calif., is approaching the end of a multiyear project called CALO, which stands for cognitive assistant that learns and organizes. CALO is financed by the Defense Advanced Research Projects Agency of the Pentagon and is one of the largest artificial-intelligence projects ever. Some public demonstrations have been given, but CALO is being developed largely out of the public eye because it is intended for the military.  There is already one quiet commercial spin-off from the project. Siri Inc., based in San Jose, Calif., plans to introduce a personal assistance service in the first half of 2009. Still in “stealth” mode, with a small private test version of its service, Siri has raised $8.5 million from two venture capital firms.  “We’re exploring concepts developed by the CALO project and applying them to the consumer,” said Adam Cheyer, Siri’s founder and vice president of engineering. He said that he expects the idea of personal assistance to gain momentum next year and that he thinks Siri will be joined by other competitors.  A different tack has been taken by the entrepreneur Patrick W. Grady. He has put together a technology team at Rearden Commerce that has already begun to reach a business audience with an “intelligent” personal assistant oriented toward travel and entertainment. It will be available early next year for nonbusiness customers as well.  Rearden is one of Silicon Valley’s most significantly financed but least known start-ups. Founded in 1999 before the dot-com crash, Rearden announced in April that it had recently raised an additional $100 million, for a total of $200 million in almost a decade. American Express and JPMorgan Chase each own 10 percent stakes.  Why might Mr. Grady and Mr. Cheyer succeed while everyone who came before lies face down with arrows in their backs? Timing, for one thing.  The promise of the Web 2.0 era of the Internet has been the interconnection of Web services. Mr. Grady says he has a far easier task today because the heavy lifting has been done by others.  “This is the connective tissue that sits on top of the Web and brings you more than the sum of the parts,” he said. “I set out to deliver on the longstanding ‘holy grail of user-centric computing,’ a ‘personal Internet assistant.’”  He promises to bring together all of the discrete online services needed for business travel that are now separate — for starters, travel, airport parking, car services, dining reservations, entertainment tickets, package delivery and video conferences.  Imagine you are on a business trip and your computer discovers that your flight will be late. It automatically reschedules your dinner in New York, informs your three guests of the change and tells you they’ve been notified.  REARDEN’S service is used by 2,500 American Express business customers, making it available to 1.6 million employees. Chase plans to start the service for its card members early next year.  One of Rearden’s first customers was GlaxoSmithKline, the pharmaceutical maker. The company has made the service available to more than 50,000 users in the United States and Britain; the service helps to plan 3,000 to 4,000 trips a week.  “We think of it as a personal executive assistant,” said Gregg Brandyberry, a vice president at the company, who counts on the service to notify his BlackBerry of changes in his schedule while he is traveling.  Thomas D. Garvey, an artificial-intelligence researcher at SRI, said CALO passed an important milestone last week when it was used in a United States Army test of a command and control system at Fort Leavenworth, Kan. CALO watches users work with computer systems and then automates routine tasks, he said. With CALO doing mundane work, he said, Army officers can focus on more important matters.  Have Mr. Grady or CALO or Siri cracked the code in the half-decade-long quest for a software personal assistant? Ordinary computer users will soon have a chance to find out.  A version of this article appears in print on , on Page BU4 of the New York edition with the headline: A Software Secretary That Takes Charge. Order Reprints| Today's Paper|Subscribe
A new generation of Internet technologies is making meaningful progress in anticipating your needs without you pressing a key.