Errata

The word "reign" should be "rein." A king has a reign; a horse's bridle has a rein. "Free rein" means the rider holds the rein very loosely and the horse can go where he wants. "Free reign"? I have no idea what that means.

Text reads "If you haven't noticed the Screen Option button yet, that's because it's carefully tucked away in the top-left corner of the dashboard (circled in Figure 4-26)." Text should read "...in the top-right corner...".

Last word, Appearances, should be Appearance.
(Yes, that's excruciatingly trivial. So sue me.)

I think "pull the widget in the" should be "pull the widget into the" -- am I right?

"old ays" should be "old days"

"used in a post.)" should be "used in a post)."

"If you're HTML" should be "If your HTML"

"optimized" should be "optimizes"

"what your heading looks until" should be EITHER
"what your heading looks like until" OR
"how your heading looks until"

Again, "free reign" should be "free rein"

"one the most" should be "one of the most"

"Pictures aren't the only file" should be "Pictures aren't the only files"

"menu item." should be "menu items."

"the most renown" should be "the most renowned"

"write web application" should be
"write a web application" or else
"write web applications"

In the third (footer) row, the final sentence talks about the header. Perhaps this sentence should be in the second (header) row?

"can't help notice" should be
"can't help but notice" or else
"can't help noticing"

"same was as child" should be
"same way as child"

Example talks about get_the_date() function, but list example:

$postdate = get_the_time('Y-m-d');

and refers to get_the_date in text.

Also when referring to previous example, notes it as simply:

$currentdate = date('Y-m-d');

but actual example is a muddle that includes mktime(0,0,0 ...)

and is unclear.