A bit dated, nonetheless ...
For those of you who are familiar with or have heard of the famous "Microkernel Vs. Monolithic kernel" debate between Tanenbaum (Computer Networks book fame) and Linus (creator of Linux), here's some interesting fodder.
Original Debate: http://www.oreilly.com/catalog/opensources/book/appa.html
Debate Time again, featured @ http://linux.slashdot.org/linux/06/05/10/0439246.shtml?tid=190
Tanenbaum reply: http://www.cs.vu.nl/~ast/reliable-os/
Interesting related reads:
Earlier Tanenbaum writeup defending Linus: http://www.cs.vu.nl/~ast/brown/