How come the flags are at half staff for some of the teabag pics and not in others?

By a joint resolution approved December 18, 2001 (Public Law 107-89), the Congress has designated September 11 of each year as "Patriot Day." On this day the American flag is to be flown at half-staff on all federal buildings. Many citizens of the United States observe Patriot Day with appropriate ceremonies, activities, and remembrance services, display the flag at half-staff from their homes, and observe a moment of silence beginning at 8:46 a.m. eastern daylight time to honor the innocent Americans and people from around the world who lost their lives as a result of the terrorist attacks of September 11, 2001.

http://www.gettysburgflag.com/FlyFlagHalfMast.php

What is the meaning of raising the flag to full mast, then returning it to half mast until noon, and then raising it to full mast until sunset on Memorial Day?

This is a very good question. The closest thing to an explanation that I know of was in the original version of the "flag code" that was adopted in 1923: "On Memorial Day, May 30, the Flag is displayed at half-staff from sunrise until noon and at full staff from noon until sunset; for the Nation lives and the Flag is the symbol of a living nation." The last clause might be interpreted as saying that the pre-noon half-staff period was to honor the dead, and the post-noon full-staff period was to symbolize that the Nation lives on.

However, the custom of half-masting the flag until noon on Memorial Day was around long before it was written into the flag code. This description is from a book published in 1906, which quotes then-current military regulations:

"On Memorial Day, May 30, at all army posts and stations, the national flag will be displayed at half-staff from sunrise till mid-day, and immediately before noon the band, or field music, will play some appropriate air, and the national salute of twenty-one guns will be fired at 12 M. at all posts and stations provided with artillery. At the conclusion of this memorial tribute, at noon, the flag will be hoisted to the top of the staff and will remain there until sunset. When hoisted to the top of the staff, the flag will be saluted by playing one or more appropriate patriotic airs. In this way fitting testimonial of respect for the heroic dead and honor to their patriotic devotion will be appropriately rendered."

Clearly, the idea was that the moment of noon ("12 M." was short for "12 Meridian") would be the focus of the symbolic tribute to the fallen. However, the specific reason for raising the flag to full mast at noon was not spelled out. (The modern US Army instruction on "Salutes, Honors and Visits of Courtesy" says basically the same thing as the 1906 language.)
http://www.usa-flag-site.org/forum/meaning-of-half-mast-until-noon-5731.html