Recently someone asked me, “Marc, I see some USB memory sticks include something called ‘U3.’ What is it and why is it important?”

U3 technology will soon evolve into something else, but let me first answer the question. Developed by U3 LLC, a joint venture between SanDisk (the makers of the popular Cruzer line of USB thumb drives and Sansa MP3 players) and m-systems, U3 smart software first became available in 2005 on select USB drives. SanDisk then acquired m-systems nearly two years ago.

U3 is Windows-based software that resides on SanDisk’s USB thumb drives and lets users carry applications and preferences that offer a secure and consistent experience among multiple PCs. This might include personalized email programs and settings info, Web browsers and Web site profiles, productivity tools, communication software (such as VoIP programs like Skype or Vonage), multimedia applications, and so on.

Typically, when you plug a U3-based flash drive into a PC, you’ll see two windows pop up. One lets you access files on the stick or copy more data to it (e.g., drive F:), and the second is to open the U3 files (on, say, drive G:), which might include the SignupShield password manager and an encryption tool to protect your files in case you lose this tiny USB drive.

Although details are vague, Microsoft and SanDisk recently announced they were joining forces to expand on and replace U3 technology with more robust tools for Windows PCs, including the addition of TrustedFlash security technology.

SanDisk says it will incorporate a new software suite on its removable flash memory cards and Cruzer USB flash drives during the second half of this year.