Microsoft has released the 5th installment of their Security Intelligence Report (SIR), full of interesting data on; Botnets, High severity vulnerabilities (both OS and Browser based), exploit and malware trends and 

Microsoft’s describes this report is as a valuable source that provides an in-depth perspective on the changing threat landscape including software vulnerability disclosures and exploits, malicious software (malware), and potentially unwanted software. 

The full report includes great data and graphs like this one explaining the trends in; malware, trojans and worms that are being seen cleaned from PCs.  
The report also includes heat maps from Global Infection rates and localized reports for a number of countries including; Canada, France, Germany and the United States.
Get the Executive summary here (1.1 MB pdf) and the full report here (12.8 MB pdf).