Creating Smoke with CC Particle Effects
You may remember Chad Perkins from such movies as After Effects CS5 Essential Training on Lynda.com. He's started a web venture Movies and Computers, which seems geared toward newer users of digital video.
Chad promises a review series of AE filter effects, and one of the first video tutorials is Creating Smoke with Cycore Particle Effects, embedded below. He's doing it a bit cartoonie and all procedural, but nice.
There's more resources on creating smoke in After Effects at AE Portal under the tag smoke. Andrew Kramer often mixes real world samples and/as particles, so check out his smoke tutorials which often use the CC effects. Also, Richard Lainhart uses Particle Playground to show you How To Create Smoke Effects in After Effects.