It could. It definitely means he likes you enough to want to introduce you to his coworkers. Maybe it's a test to see if you're dating material. Or it could just be that he wants a fun, laid back friend at the party to make the awkward work banter more bearable. Sometimes being single at company functions can be depressing, particularly if everyone else brings someone. It's like a wedding in this way, only with more snowflake cookies and Ted from accounting passed out in the corner. Plus, having you there makes the party more lively and, well, less like being at work.
Either way, it's definitely a sign that he enjoys your company and trusts you to act appropriately around his coworkers. First, you should read my handy guide on the dos and don'ts of office holiday parties. Then when you get to the party, follow his lead. If he's comfortable drinking around his coworkers, feel free to drink as well. If he's avoiding talking to Suzy in marketing about the adorable sweaters she knits for her cats, make a beeline for the snacks whenever she comes by. The more you pick up on his cues at the party, the more brownie points you'll earn, and the likelihood of him inviting you to future functions (or maybe asking you out) will increase.
If you're looking for more than friendship, this could be a good opportunity to bring out your A-game. Wear your hottest, though still office party-appropriate, outfit. If it's a potluck party, ask him if you should bring anything. And if the party is mind-numbingly awful, be ready with a suggestion for something fun to do instead. (Even if it's just getting hammered at the local bar.)
Who knows? Maybe this is will be the moment when he suddenly realizes he's deeply, madly in love with you. You'll crack a joke about the terrible clam dip and he'll look up, past Suzy and her picture of Mr. Meow-stoffelees in a snazzy Christmas sweater, and suddenly see the woman he's going to spend the rest of his life with.
Or you'll have a fun time with a pal and get free booze and snacks. And maybe a funny story or two about his crazy coworkers.