Lockhart is a bumbling idiot - except when it comes to memory charms, and he was so driven to be a famed writer that he used inscrupulous means to obtain his status as star autobiographical wizard and hero. So, how on earth does one explain his being sorted into Ravenclaw? Doesn't his level of ambition and the use of tricks in getting there seem more fitting for Slytherin?
One might argue he is intelligent in his ability to pull of his ruse for so long, but Ravenclaw qualities that are valued are intelligence and wit. These forms of "cleverness" (another value) are usually associated with a high degree of knowledge, the ability to problem solve and bandy about with riddles and turns of phrase. One part of wisdom or intelligence though, can also include an understanding of your limits and knowing when others are better suited to something - something Lockhart can't let happen. His ambition drives him to try to "fix" things best left to others (such as Harry's broken arm).
I'll admit Lockhart must have been fairly good with words (wit) to have written and published so many books so the wit part might fit, but I just don't see any other way that he fits with the Ravenclaw quality list.
Apparently Slytherin values ambition and cunning (which is a type of cleverness associated more with the fox - a kind of "tricky intelligence.) While cunning is also a form of intelligence, it seems more fitting to the type of intelligence Lockhart did exhibit. Between this fact and the fact that he left other witches and wizards without their memories (and who knows in which state of mental deficiency based on what his memory charm did to him when it backfired) for his own gain, I'm really at a loss as to explaining how he could wind up in any house other than Slytherin.