What kind of U.S. Army uniform is this?

As shown in photo 24 in this sequence from the recent State Dinner at the White House:

http://www.washingtonpost.com/wp-dyn/content/gallery/2009/11/24/GA2009112403521.html

It looks like an Army Blue Mess Jacket of some kind.

The Army Mess Blue worn by a social aide Major of the Artillery (I presume those odd purple lapels are supposed to be Artillery red.)

Agreed. It’s the Army Blue Mess Uniform. The lapel color is indeed the branch color, though what that maroon-ish color is supposed to be, I don’t know. You can’t see his suspenders, but those would also be in the branch color.

It may be JAG. I know purple is the color of law.

Dress Greens Out, Dress Blues in for Army

In academic regalia, that is.

It’s the Civil Affairs and Psychological Operations branch.

I believe it’s the catering branch of the New Earth Army.

Warning: PDF link follows!

Army Regulation 670-1

See Chapter 24, Army Blue Mess and Evening Mess Uniforms—Male.

Paragraph 24-5 states that General Officers, except Chaplains, will have dark blue lapels; all Chaplains will have black lapels; all other officers will have lapels of the first-named color of their branch (as listed AR 670-1, para 28-19); and all Enlisted personnel will have dark blue lapels.

Here is the list of branch colors for lapels as found in paragraph 28-19:

As one can see, purple is only assigned to the USAR Civil Affairs branch while the JAG Corps has dark blue lapels.

The regulation linked above is dated 3 February 2005.

p.s. to Turble: Dress Blues (real name: Army Blue Uniform) and Blue Mess are two different uniforms.

This might be of interest; those Marines have it goin’ on!: http://en.wikipedia.org/wiki/Mess_dress

Looks like they’ve finally abandoned “don’t ask don’t tell.”

The Branch Immaterial? Is that like the Choir Invisible?

Plus, they were never “Dress Greens”, just Class As.

What does a “no color assigned” lapel look like, I wonder?

Dark blue.

Looks a bit like a drum major in search of a parade.

There is only one Sergeant Major of the Army. I would assume he would wear the color of the branch he was in before he got promoted to SMA.

Likewise, general staff personel would wear the colors of the branch they were in before they were assigned to the general.

The Sergeant Major of the Army is an Enlisted member. As such, he would have dark blue lapels.

The cut of that jacket doesn’t match here:
http://downloads.army.mil/docs/asu/dress_classa_lo.jpg

I also wish to point out that Army hats are doofy.