"Le Rubis" (10 Rue du Marché Saint-Honoré) could be a good spot. A very traditional bar with links back to the region. Their selection of "proper" Beaujolais is very good.
If you are looking for serious "nouveau" you could try "Fish la Boissonerie" (69 rue de Seine) they often have a bio/organic (?) wine from a serious producer which shows nouveau in its best light. I was quite cynical about it as a wine until I tried the one they had a few years ago, it showed that a serious producer can get something interesting from this style. Certainly there is lots of horrid commercial nouveau around but a few producers are doing some interesting things, maybe a return to the original (nob-commercial) roots that started all the fuss?
Other suggestions, maybe search (pn the board) for other bio/organic wine bars, there are a few around and if they have nouveau it is likely to have far more "soul" than general bars.
Folks, we've removed a number of off topic replies, and if you'd like to share your thoughts on Beaujolais Nouveau, the wine, please start a new thread on the Wine board. This poster is asking for recommendations on where to enjoy the wine in Paris, so please keep your recommendations here restricted to that topic. Thanks.