2008 LC18.

http://www.dtm.ciw.edu/users/sheppard/L5trojan/2008LC18.html . From Subaru; note the extremely crowded starfield. Certainly illustrates the difficulties faced by NH's KBO target search in the same general line-of-sight region at this time.

It's a trailer, est. 60 km 'diameter', orbit apparently a bit inclined. Early reports indicate that NH won't get close enough to get a good look at it when it passes through this Lagrange point in a few years, but the search continues for others.

First trailing trojan, you mean? Or because this is 2008-tagged, are you just sharing the photos? Crazy they could find anything.

First trailing Trojan, not the first trojan in general (some have been found in Neptune's leading Lagrange point).

Emily explained this very well on her TPS blog:
http://www.planetary.org/blog/article/00002623/

Yeah, mea culpa... did indeed mean first trailer (L5). Can an admin please fix the title?

Emily did do an outstanding job on her blog, as per her usual excellence in reporting!

EDIT: Thanks for fixing the title, Unknown Admin!

The notion that there could be enough of these Lutetia-sized objects in the Neptunian LaGrange points to equal the combined mass of the main asteroid belt really sounds surprising, until you bring in the notion of outward migration. Observations up to this point seem to indicate that Saturn and Uranus have fewer LaGrangian companions than Jupiter and Neptune. If I am reading correctly between the lines of Emily's account, I guess Neptune had the first opportunity to sweep up the rubble as the big planets migrated outward. Jupiter, being so massive, probably had some advantage capturing the rest.