Symantec acknowledges that  Microsoft’s having the shortest average patch development time:

“Of the five operating systems tracked in the first six months of 2007 (figure 18), Microsoft had the shortest
average patch development time at 18 days, based on a sample set of 38 patched vulnerabilities. Of the
38 vulnerabilities, two affected third-party applications. This is lower than the average patch development
time of 23 days in the second half of 2006 based on a sample set of 50 vulnerabilities, seven of which
affected third-party applications.“

Symantec Internet Security Threat Report
Trends for January–June 07
Volume XII, Published September 2007
Page 54
Link: http://www.symantec.com/content/de/de/about/downloads/PressCenter/ISTRXII_Main.pdf

Well... ;-) but, there are also other interesting topics covered.

Urs