I'm a big fan of 'sar' as well. It's nice that it can also show you i/o wait for the sampled period. I also love vmstat, as you can use it to see everything that is happening with the system sampled every second if you like. The first two columns will show you the number of processes in the run queue as well as number of processes blocked on i/o.

sar gets its info from /proc/loadavg (on Linux OSs), just like top and uptime do, which is produced using the same code the article shows.

We must be running different versions of sar then, as "sar" by itself here (RHEL 5) shows information about the time split between user/system/waitIO/idle -- that certainly does not come from /proc/loadavg.

If you run "sar -q" you could get the load average information, but that's not particularly useful, as you can't see whether the 20 load avg an hour ago was caused by heavy disk IO or a dozen CPU bound processes.

Nope, we're likely running the same version. The particular info you mentioned comes from /proc/stat (you're right that it's a different file), but again it's the same sources as top:

    # lsb_release -d
    Description:    Red Hat Enterprise Linux Server release 5.3 (Tikanga)

    # rpm -qf $(which sar)
    sysstat-7.0.2-3.el5

    # strace /usr/lib64/sa/sa1 1 1 &> results

    # grep open results                      
    open("/etc/ld.so.cache", O_RDONLY)      = 3
    open("/lib64/libtermcap.so.2", O_RDONLY) = 3
    open("/lib64/libdl.so.2", O_RDONLY)     = 3
    open("/lib64/libc.so.6", O_RDONLY)      = 3
    open("/dev/tty", O_RDWR|O_NONBLOCK)     = 3
    open("/proc/meminfo", O_RDONLY)         = 3
    open("/usr/lib64/sa/sa1", O_RDONLY)     = 3
    open("/etc/ld.so.cache", O_RDONLY)      = 3
    open("/lib64/libc.so.6", O_RDONLY)      = 3
    open("/etc/localtime", O_RDONLY)        = 3
    open("/sys/devices/system/cpu", O_RDONLY|O_NONBLOCK|O_DIRECTORY) = 3
    open("/proc/tty/driver/serial", O_RDONLY) = 3
    open("/proc/interrupts", O_RDONLY)      = 3
    open("/proc/net/dev", O_RDONLY)         = 3
    open("/proc/diskstats", O_RDONLY)       = 3
    open("/var/log/sa/sa06", O_RDWR|O_APPEND) = 3
    open("/proc/stat", O_RDONLY)            = 4
    open("/proc/meminfo", O_RDONLY)         = 4
    open("/proc/loadavg", O_RDONLY)         = 4
    open("/proc/vmstat", O_RDONLY)          = 4
    open("/proc/sys/fs/dentry-state", O_RDONLY) = 4
    open("/proc/sys/fs/file-nr", O_RDONLY)  = 4
    open("/proc/sys/fs/inode-state", O_RDONLY) = 4
    open("/proc/sys/fs/super-max", O_RDONLY) = -1 ENOENT (No such file or directory)
    open("/proc/sys/fs/dquot-max", O_RDONLY) = -1 ENOENT (No such file or directory)
    open("/proc/sys/kernel/rtsig-max", O_RDONLY) = -1 ENOENT (No such file or directory)
    open("/proc/net/sockstat", O_RDONLY)    = 4
    open("/proc/net/rpc/nfs", O_RDONLY)     = -1 ENOENT (No such file or directory)
    open("/proc/net/rpc/nfsd", O_RDONLY)    = -1 ENOENT (No such file or directory)
    open("/proc/diskstats", O_RDONLY)       = 4
    open("/proc/tty/driver/serial", O_RDONLY) = 4
    open("/proc/interrupts", O_RDONLY)      = 4
    open("/proc/net/dev", O_RDONLY)         = 4

    # strace top -n -b 1 &> results
    # grep open results 
    open("/etc/ld.so.cache", O_RDONLY)      = 3
    open("/lib64/libproc-3.2.7.so", O_RDONLY) = 3
    open("/usr/lib64/libncurses.so.5", O_RDONLY) = 3
    open("/lib64/libc.so.6", O_RDONLY)      = 3
    open("/lib64/libdl.so.2", O_RDONLY)     = 3
    open("/proc/stat", O_RDONLY)            = 3
    open("/proc/sys/kernel/pid_max", O_RDONLY) = 3
    open("/etc/toprc", O_RDONLY)            = -1 ENOENT (No such file or directory)
    open("/root/.toprc", O_RDONLY)          = -1 ENOENT (No such file or directory)

If you don't already know about it, dstat is a good one too, and lightweight enough that it can be run on heavily loaded production systems w/out as much "top problem" going on.