Originally "infosnacking" described time spent on the computer at work doing things that aren't work-related, such as Googling someone or shopping online. Like all great Internet terms "infosnacking" has morphed to describe the practice of jumping online for brief periods throughout the day (wherever you are) to check e-mail, sports scores, or headlines.
BTW: Even though it was nominated as the word of the year in 2005 by Webster's New World College Dictionary (not the same as Merriam-Webster), "infosnacking" is not widely used in online jargon or in the real world. In fact the editors don't even plan on adding it to the dictionary; that doesn't make any sense. Sources tell us their reasoning is because "the word of the year isn't about popularity...we choose a word that tickles our linguistic funny bone or is significant in the way language reflects culture." On the contrary, we at NetLingo think "anything of the year" should be about popularity and apparently so does the New Oxford American Dicitonary who nominated "Podcasting" as the 2005 word of the year. As of December 8, 2005, "infosnacking" was getting a mere 637 hits on Google while "Podcasting" was getting more than 35 million. So if it's a popularity contest, it's pretty clear who wins.