This is J.Crew Outlet's version of the Embroidered Carmen Tank (item #91334), which was available last spring/summer from J.Crew's Vintage Closet line. The original tank retailed for $88, and the outlet version is marked $54.50. The retail and outlet tanks have the same item number. I actually ordered this tank last summer on some type of sale, picking it up for $31.99.
It also has another cute detail - on-seam side pockets, which I also love. The pockets hit right about at your waist (at least for me).
I think this tank works great alone or as a layering piece. I think J.Crew did a great job adding the sweet detailing that makes this tank more than just a soft, somewhat boxy or shapeless tank. I didn't take this one home because I already have one (albeit in a different color and size), and the price was a bit too high for me. Hopefully it will go on sale soon!