It's part # 8 on the following image. Parts # 10 and # 11 are also bolted on part # 8 and came as one part all together.
http://www.geocities.com/silenttype76/b-pillar.jpg
But home from work today I crashed my Boxster, destroying the front bumper spoiler, the left side head light, the left fender and the left radiator. So now I guess I got more than the B-pillar to worry about....
