At this point I think there are as many documentaries about Star Trek as there are Star Trek movies.
I'll be honest with you, I have very warm childhood memories of Trek, and I like the movies, but I am not a Trekker, I'm a bit more of a Trekkie. I rarely get to watch reruns of either the original series or Next Generation. I never watched much Voyager, DS9, Enterprise or the short-lived Animated Series.
I have, I suppose, muted enthusiasm for certain brands of Trek, especially those that weren't overseen by Gene Roddenberry.
Trek Nation (2010) isn't actually about the fandom of Star Trek, but the relationship between Star Trek creator Gene Roddenberry and his son, Rod Roddenberry, and Rod's discovery, as an adult, of the impact his father had on the world.
Sure, the Sci-Fi conventions are all there. The geeks in their Klingon suits get coverage, a few of the aging stars of the franchise get some camera time and interview terrifically well, but far fewer of them than you'd expect. But to ask Shatner to reminisce about who Gene Roddenberry was isn't really the focus. You do get just an astounding amount of behind the scenes footage, archival stuff, candid stuff... its impressive what they dug up.
The interview subjects also include series writers like DC Fontana (turns out DC is a lady. I did not know, but very in keeping with Trek, I think), George Lucas and Stan Lee talking about the impact of Trek and a bit of why it worked, and what that might have said about Roddenberry the Sr. Also included are writers and producers from the later series, leading right up to JJ Abrams talking Trek with the son of Roddenberry.
That Rod Roddenberry so clearly did not know the man with whom he lived until his father died in 1991 is in every bit of the movie, and even if it can tilt toward familiar hagiography at times, its through the eyes of the grown man both thrilled and injured to see his father's legacy and he becomes a part of it.
I do wish they'd dug a bit deeper, perhaps. There are some ellipses that could have used a full stop when it comes to how and why the Roddenberry men weren't close, but it doesn't feel incomplete.
I caught this as a two-hour broadcast on the Science Channel, just FYI. I wasn't sure if it counted as a movie of 2012, but I'm counting it.