Greg Kroah Hartman did a techtalk at Google recently. Some interesting stats related to the Linux 2.6.25 kernel development effort:

• 2399 contributers over last 1.5 years
• 1/2 of these have done one patch, 1/4 did 2
• 9.2M Lines of Code
• 10% year over year lines of code growth
• ~55% of code in drivers - majority by a small bit, but not all drivers.
• Change rate of kernel code to driver code is proportional. Translation: the core of OS is changing at a crazy rate.
• New releases every 2.75 months or so
• 9000 symbols and 12000 data structures inside the kernel (below the syscall layer)
• Rate of change is insane
• 4300 lines added
• 1800 lines removed
• 1500 lines modified

• PER DAY!!!