The keyword in the wikipedia article is "simple kind" of jail mechanism. Yes indeed it is. As others above have pointed out, if you do not run the processes as root, and do not have setuid processes in the chroot'ed env, then it is a "simple kind" of jail mechanism. However, do silly things like run daemons as root , by all accounts not something that should be considered part of the "simple" realm in Unix, and due diligence would dictate that you re-examine your simple assumptions.
All over the web, man pages, O'Reilly books, and university courses it is said that root is dangerous and must be treated with the utmost respect and care. I think it is obvious from the very philosophy of root that that warning should supersede any other information you may read on a man page of a program.
Also from Wikipedia http://en.wikipedia.org/wiki/Root_user
Software defects which allow a user to "gain root" (to execute with superuser privileges code supplied by that user) are a major security issue, and the fixing of such software is a major part of maintaining a secure system. One common way of gaining root is to cause a buffer overflow in a program already running with superuser privileges. This is often subsided in modern operating systems by running critical services, such as httpd, under a unique limited account.
And in the same wikipedia article referenced, http://en.wikipedia.org/wiki/Chroot, ignoring the changes from today in obvious reaction to this slashdot posting, you will read under limitations:
Only the root user can perform a chroot. This is intended to prevent users from putting a setuid program inside a specially-crafted chroot jail (for example, with a fake /etc/passwd file) that would fool it into giving out privileges.
The chroot mechanism itself is not entirely secure on all systems. On some systems, for example, chroot contexts do not stack properly and chrooted programs may perform a second chroot to break out.
This warning or some variant of it, has been part of the article on chroot since July of 2005 http://en.wikipedia.org/w/index.php?title=Chroot&diff=19562594&oldid=19544086