While the organization's name is properly spelled with a capital W and L, the English word is simply "wikileaks."
And it's true that there's no official governing body for the English language; rather, popular usage itself is the arbiter of new vocabulary.
We're not surprised by the revelation that WikiLeaks has been on many a tongue recently; people are talking and writing about WikiLeaks at incredible volumes this year.
And the organization's (and its founder's) exploits haven't just captured the minds of the tech set, either. Julian Assange made a faux-appearance on Saturday Night Live this past weekend — if that's not a zeitgeist for popular culture, we don't know what is.
Nevertheless, the word has yet to become a trending topic on Twitter; Twitter reps say the mentions of WikiLeaks haven't yet made the grade when it comes to volume and velocity.
Other words, such as "google" and "friending," have become commonly used as verbs. While the former was a proper noun and company name, most of us (with the exception of Steve Ballmer and a few others) don't mind saying that we're going to google a search term these days.