Aha you're right. That's a terribly unsatisfying description. I won't pretend to be an expert on language poetry, but here's what I remember learning in class:

Language poetry has two big defining characteristics that stick out to me distinctly. First, it does indeed place huge emphasis on the reader. In practice, this means that the author gives the reader very little to work with. Usually this means poems with no context, a lack of coherence, language and sentences that don't seem to make any sense, etc. The idea is that the reader does all the work in giving the poem meaning. There is nothing, or little, that can be deciphered in these poems. Instead the focus is heavy on creating something unique between the text and each reader. The idea is that the poem will spark something different or special for everyone. The author, in fact the idea that any person is behind the poem and dictating it is as removed as possible in order to facilitate this.

The second primary characteristic is that a lot of language poets like the idea that poetry should not be slaved over, meticulously crafted, or even deliberately written. They do things like create poems by literally copying a newspaper article word for word, and inserting line breaks and new punctuation to give it new meaning. A great example is the poet Jackson Mac Low, who created a poem called "Is That Wool Hat My Hat?" According to an interview we read for class, Mac Low was at a show where he overheard one person ask another the question, "Is that wool hat my hat?" The phrase stuck out to him. He assigned each word a number between 1 and 6, and rolled a die a lot of times to determine in which order the words should fall. Each line of the poem is the same six words in a randomized order. He wrote it as a performance poem for four people to present together, each one chanting his/her own unique set of lines of the same six randomized words simultaneously for a few minutes. I found a video here! It is kind of madness, but that is indeed how it was written to be performed. I have a copy of pages form Mac Low's own book with the very instructions, which I can post when I get home in about a month. So anyway, the point is that the phrase itself holds almost no meaning, and took a few minutes of dice rolling to create, but meaning is created in the moment that people perform it together.

Because language poetry is often non-compositional, like jumbled up newspaper articles or phrases thrown together by rolling a die, many academics and poets regard it with disdain. They view it as anti-art, and not as poetry at all. It is a controversial subject. The professor who taught this class, however, thinks language poetry is very fun, and is a big fan of how it works. She is currently compiling an anthology of poetry for undergrads studying the English. She has actually included a lot of song lyrics, including "Kid A." She said that the song lyrics and the language poetry is where she has encountered the most resistance with her publisher. I believe the book is to be released this month. Personally, I find language poetry frustrating. I really like the idea behind it, but I always find myself annoyed and as though I haven't come up with much. Maybe I should keep trying, or maybe it just isn't for me.

I think this makes the Wikipedia article a little bit clearer. The style emphasizes disjunction because there is an intentional disconnect between reader and author, between sentence structure and how we usually speak, between the idea that poetry is crafted and what the poet is giving you, and indeed between each word and line of the poem. It is all very disjointed and feels unnatural or unintuitive. These poems focus on materiality and the physical world in that they distort everyday things like questions about hats and newspaper articles. I'm not so sure about the rest though.

I hope this gave you a little bit of a better handle on language poetry. When I get back home (I'm studying abroad right now) I will be able to get into my folder from the class and provide you with more examples if you'd like! But right now I'm having trouble finding/remembering the poems and poets.