Thanks to new adventures in data loss, a number of employees at Microsoft and Apple weren't exactly kicking back on Columbus Day.

A much-publicized outage this weekend meant that many Sidekick smartphone owners found their contacts, appointments and photos had disappeared into thin air. While Sidekick is sold by T-Mobile, the wireless carrier hasn't been taking as much heat for the incident as Microsoft, considering that a server failure at the Redmond company's Danger subsidiary was to blame.

"T-Mobile and Microsoft/Danger continue to do all we can to recover and return any lost information," explained T-Mobile on its Web site. The company also added a cautious note of hope Monday: "Recent efforts indicate the prospects of recovering some lost content may now be possible." T-Mobile, which wasn't all that prompt in responding to the outage, also extended a $100 "customer appreciation card" to stricken Sidekick users, though that hasn't appeased many.

But T-Mobile's customer service isn't the story here. Much like Google's recent Gmail outage caused a feeding frenzy among tech writers and columnists, Microsoft's failure has spurred many to suggest that cloud computing just isn't working out.

Microsoft bought smartphone maker Danger last year for $500 million in a move that looks like a mistake -- the phone, which has about 1 million users, isn't a hit, and now Microsoft's various cloud ventures are likely to take a PR black eye. Sidekick is designed to hold only the most recently synced data, with the rest residing on the cloud. But, according to Reuters, "a confluence of errors from a server failure ... hurt its main and backup databases."

A Washington Post blog pulled few punches Tuesday: "It is one of the few times a cloud computing vendor didn't have offline or off-site backups that could survive a server implosion -- even though the Sidekick's design leaves users without any easy way to copy their data to their own computers, and even though Microsoft and Danger should have thought to run an extra backup cycle when a bout of service glitches set in a week before Sidekick data vanished."

With the Azure cloud computing service, Microsoft is making a big investment in the cloud. And the company's Office Web Apps -- its answer to Google's suite of online applications -- will soon offer businesses an opportunity to work on documents both in the cloud and on premises. Though the Sidekick data center was entirely separate from these, the incident could leave a bad taste in the mouth of Microsoft's potential cloud customers.

Meanwhile, Apple has been having data woes of its own. Since the late August release of the Snow Leopard operating system, some users have complained of a particularly nasty "feature." When they logged on to their computer using a guest account, it wiped out their personal data. Loathe to admit actual problems with its technology, Apple finally issued a terse admission Monday, telling CNET that "we are aware of the issue, which occurs only in extremely rare cases, and we are working on a fix."

The bug does appear to be fairly uncommon, given that Mac owners haven't yet taken to the street, but it does sound like a true nightmare. As one Snow Leopard user posted on the Apple support board: "I accidentally logged into my Guest account this week and it, too, was taking a long time to connect. So rather than wait/walk away, I clicked on my account icon on the screen, which stopped the Guest log-in. When I went to my account, the desktop screen was reset to factory and ALL DATA WAS GONE."