While the Sidekick isn't really a business device (and it stores most data online rather than on the phone), this does serve as a cautionary tale for anyone walking around with precious, irreplaceable data. Here's how to protect yourself against a Sidekick-style calamity:
Sync ItIf your phone syncs with Outlook, Exchange, and/or some kind of corporate server, you're probably in good shape. The very process of syncing creates a backup that can be accessed on your desktop, or at the very least restored to your phone.
That said, I know plenty of people who enter data only on their phones and never bother to sync them. (I've even met iPhone users who've never bothered to install iTunes!) Big mistake. Make syncing a daily, or at least weekly, habit.
Print a Hard CopyEvery few months, I print my address book. Then I print my calendar. Paper can survive even the worst catastrophes (well, not fire), so even if your phone gets lost, busted, or wiped by a carrier boo-boo (cough, T-Mobile, cough), you'll still have your most important data. Hey, manual re-entry beats trying to recreate everything from memory.
Outlook, Palm Desktop, Google Calendar -- these and other tools let you print whatever you want. Take advantage of that option.
Make Online BackupsA variety of services make it a cinch to wirelessly back up your data to the cloud. For example, there's Microsoft My Phone, a free service (just out of beta, by the way) that provides automatic daily backups of your Windows Mobile phone.
Android, BlackBerry, and Windows Mobile users can check out Skydeck, which syncs your contacts, text messages, and call history to a Web-based portal.
And then there's Mobical, a phone-backup service that works with all SyncML-compatible phones (meaning most models from LG, Motorola, Nokia, Samsung, and Sony Ericsson).
Finally, check with your carrier to see if it offers a backup service. Even if it does, consider supplementing it with one or more of the aforementioned options. Because, let's face it, you can't have too many backups.