There is one, it's called the CPN or Carnivorous Plants Newsletter. Unfortnately you can only get it by joining the ICPS International Carnivorous Plant Society, not at any retail news stands or bookshops.
I have often wanted an exotic plants (not just CPs) magazine to buy but there is nothing for us plant freaks, or freak plant freaks!
I am an independent publisher by hobby/trade and about 1-2 years ago I was trying to get the publisher of Uner het Palmblad (translated: Under the Palm Blade -
www.palmbald.nl) to publish his quarterly exotic plants/terrarium magazine in English (translated from Dutch). I offered to do all the press/distribution and retail services however he found the cost of US printing to be highly prohibitive in comparison to printing with Belgian companies. The only problem printing there is transport costs from Belgium to the US, unfortunately the English edition idea was scrapped altogether.