Numerous reports of new malicious PDFs have come out in the last few days. They all seem a little different and, while there are no new vulnerabilities in them, there are some new techniques.
The TrendLabs Malware Blog describes a PDF that it found, which exploits two different patched vulnerabilities. If you are running current Adobe software, you are not vulnerable. But if you do get exploited, the PDF decodes an embedded XML file containing a malicious TIFF file.
The most important thing to know about all these attacks is that by keeping your software up-to-date and not blindly clicking on unsolicited attachments, you can protect yourself, at least to a significant degree. Add updated malware protection to the mix and it's even harder for attacks to succeed.