The service caters to Windows PC, Mac, iPhone and iPad owners, who use it to synchronize address books, calendars and e-mail between devices. The service also offers 20GB of online storage space, as well as Web-based e-mail, calendar and contact applications.

MobileMe, which was priced at $99 for a single user membership and $149 for a five-user family pack, has disappeared from Apple's e-store. Search results from, say, Google, now lead to invalid pages on Apple's site.

Users can still sign up for a of MobileMe, however.

Some have connected MobileMe's vanishing act with news yesterday from Apple's annual stockholders meeting, where COO Tim Cook said that the company's would open this spring.

"I think they indicate changes ahead, which would be good," said Ezra Gottheil, an analyst with Technology Business Research. "MobileMe has been a fairly lackluster service, and never offered the bang for the buck that people wanted," he added, noting that many of the same services are available from Google and others on the Web for free.