The Jargon File is correct, but somewhat outdated. The term newbie has gradually achieved wider recognition and use, and could now be used relative to any activity or field. This is especially true of anything to do with computers or the internet. A newbie, depending on context, could be new to the internet, new to a site or online community, new to a game, or new to a fan or interest group.
The term is sometimes used pejoratively (newbies are like kids running around getting in the adults' way), but need not necessarily be. The image could also be of someone just starting out, who needs to be helped along kindly.