Active exploits using the recently discovered bugs in PDF files have been seen in the wild. Core Security reported one of the bugs back in May and recently published sample Proof of Concept (poc) code showing how the bug can be exploited. Hackers have apparently modified the poc to evade AV detection and started sending infectious PDF files in SPAM. Early on in the release phase of this bug, no AV products were able to detect the infectious PDF's. If you're running Adobe Acrobat Reader 9, you're safe. If you're running Adobe Acrobat Reader prior to 8.1.3, you'd better update immediately. It's free and you should check this often as this isn't the first time PDF's have had bugs that are actively being exploited. Just an FYI...
This exploit is in the wild too! I've heard it's been attempted from several websites. Best to patch while you can