First off, I am not certain whether people still call them webzines or not. That sounds like a very mid-90's thing to call something, much like referring to the infobahn.
In any case, I've seen a lot of tweets (thanks to that horrible, horrible concept of an election we are currently undergoing) linking to online magazines. And I've slowly come to realize that the past, and future, of online magazines can be encapsulated in its two major pioneers: Slate and Salon.
Both magazines were started in the mid-90s ('95 for Salon, '96 for Slate); both were current affairs-style news publications heavy with center-left analysis and embracing new media with old journalistic standards. They both had the same target audience: upper-middle-class youngish white intellectuals. Both launched a failed pay-per-use system for generating revenue. Both quickly branched out to cover lifestyle and occasionally revamp their interface and system. And yet to look at them today is to see vastly different products.
Neither is, of course, perfect. But it's pretty clear that Slate has emphasized pragmatic liberalism and a diffuse subject base, while Salon has retreated into a shrill progressive circlejerk.
Let's look at Slate, first. As of this writing--which, due to the nature of online information, will be different twelve hours from now--the feature articles three main politically neutral yet provocative articles (the Supreme Court, combating child sexual abuse, and an article about copyright law), and five sidebar stories (two vaguely anti-Republican stories, one snoozer about a book, one vaguely anti-Obama/foreign affairs story, and a pro-reform campaign finance story). There's also a scrolling story bar at the bottom that has too much range to detail, but it travels from the NFL to prime time TV to Newt Gingrich, so it's a scattered lot. But you get the idea: mostly politics, liberal slant but not unreasonably so, an emphasis on popular culture, and some intellectualism spiced in there. It hits its target audience perfectly: somewhat affluent and technologically inclined intellectuals, probably liberal in nature; yet the articles won't offend too many conservatives.
Salon, by contrast, rapidly turned onto a sour tabloid-like political magazine, making no particular pretense at being open to all political persuasions. Salon's setup is a little different, but the current sidebar has five stories; four clearly anti-GOP, one somewhat neutral. The "main" leader, sadly, is only one article--about the (gasp!) perils of hiring a babysitter; the rest scroll down like a sad ticker-tape of failed journalism student submissions. A make-news gourd of a piece about some whackjob who "de-liberalizes" the polls? Clearly he represents all of mainstream conservatism, so better throw him up as a headline. Three breathy articles about sex: one painfully excited about sex ads in the Village Voice, an advice column telling bisexuals to be comfortable with who they are, and an article redefining what plastic surgery makes the perfect woman. Throw in a few TV-related articles and a do-gooder liberal-stamped puff piece on education, and you have Salon in a nutshell.
OK. Maybe I'm a little too soft on Slate and hard on Salon. Slate branched out on some pretty awful sub-magazines whose empty opinions are embarrassing to read (The XX Factor, which is full of lackadaisical open-mouthed feminism, is particularly rough to read if you believe any of the writers aren't first-year Women's Studies students.) Their lifestyle articles tend to be written by clueless white suburbanites discovering life without the help. In fact, "clueless" is a pretty good adjective for Slate; the articles all seem very interesting and informative if they're related to policy, history, and social science; but if they try their hand at practicality, like workplace realities or cooking modest meals, it's almost hysterically useless. And Salon was never high culture, so perhaps there's a little bit too much expectation.
It is worth stopping and noting at this point that yet another big-scale general interest/current affairs publication is part of the new information literati, and that is The Atlantic. I didn't really include it in this comparison because they were started over a century ago as a dead-tree publication, and in fact still is in print and doing well. Its setup and core audience is much like Slate's, and I recommend it, but it's outside of the scope of this post.
Still, I think it's clear that the two web sites have seen their trajectories get farther and farther apart. Slate, for all its flaws, tries to be comfortable in its New Democrat clothes, yet internet-brave enough to wander outside of the conventional wisdom. Salon, on the other hand, revels in its poorly-written partisan hackery, willingly trading highbrow reflection over crowd-pleasing saber-rattling.