Actually, yes... sort of.
The business relationship between Wikipedia and WikiLeaks is extremely tenuous and indirect - one of Wikipedia's co-founders, Jimbo Wales, owns a company called Wikia, Inc. that employs several other people who have been closely involved with Wikipedia over the years. Wikia owns the domain names wikileaks.com, wikileaks.net, wikileaks.info, and wikileaks.mobi, and until just recently they were all redirects to the main WikiLeaks site at wikileaks.org. Wales now claims that these domains were purchased "defensively," and that they've been "trying" to transfer the domains to the WikiLeaks organization for several months, but that WikiLeaks hasn't filed the necessary forms to complete the transfer. (But then, why would they, when there's a company willing to redirect the non-.org domains for free? Some hosting sites charge up to $5 per month for domain redirects. And why would Wikia even do that if they'd bought the domains "defensively"? If I owned an internet company called "Yawoo, Inc." or "Yahu, Inc.," would Yahoo.com redirect yawoo.net or yahu.info to my website for any reason at all, and for free? I don't think so!)
All that aside, the real relationship between Wikipedia and WikiLeaks is philosophical. In the past, Wikipedia was a popular place for people to go who wanted to obtain cheap and easy revenge on people they disliked, but in recent years they've started to take themselves a bit more seriously and have made that more difficult. People still looking for that kind of revenge have had to find other, similar outlets, and that's where WikiLeaks comes in.
However, it should be noted that WikiLeaks is actually more responsible and ethical than Wikipedia or similar sites, generally speaking - they seem to be willing to apply some form of loose pre-publication editorial control and review to everything they "leak," whereas Wikipedia didn't do that at all until recently, and now only does it for a handful of articles, currently on a "trial" basis. Specifically, WikiLeaks responded to concerns about physically endangering diplomatic and intelligence informants by promising to redact names *before* publication. Wikipedia will sometimes redact names *after* publication, but by that time, it's usually too late, the cat's out of the bag.
Secrecy is usually bad, but divulging and publishing secrets irresponsibly is usually worse. Nobody should have to die or be forced to flee his country just because some low-level functionary or enlistee thinks he knows how to determine "right and wrong" better than anyone else.