You mean Liam Neeson? Ewan McGregor has been doing well enough for himself. Natalie Portman is coming off an Oscar win. Samuel L. Jackson is still Samuel L. Jackson. Ray Park still has plenty of work. I would say Jake Lloyd is the only one out of that series to completely fail.
What about pretty much everyone except for Liam Neilson in the Star Wars Prequels? We had a whole thread on what happened to Jake Lloyd awhile back (he crashed and burned harder than any example in this thread).
Also, most of the people from the Twilight series will probably be screwed, except for maybe Robert Patterson.
As for Twilight, Taylor Lautner is going to be the only one that fails to segue to something else. Kristen Stewart was already popular before she was ever signed on.