I must say, @Twinstream's post has me intrigued as well. I might look into it just for the sake of learning it, but my business model is such that I never build client's websites and then "hand them the keys" as it were. I figured out years ago that freelance website building was way too unpredictable to rely on it as a steady source of income. So, I sell websites as a "service" rather than a product. And the service is ongoing because it provides continuous value.
Broken down, I will build people a website basically for free (or a small setup charge on very complicated projects) and they sign a one-year agreement to pay a monthly fee (auto-billed via credit card) that basically works out to what I'd charge them if I built them the site up front and handed it off. This way, they get a site up online without having to pony up thousands of dollars up front. I even give them one free email account.
During the year, I will do any reasonable changes or updates they want done for no charge. I monitor their traffic, provide quarterly reports, help them integrate social media and update their Google Business and Maps info, design and run ad campaigns (extra free), adjust SEO as needed, and basically provide 24/7 service. I ensure them that they will rank within the top three in their local search on Google within three months (normally I get them to #1.)
If they cancel before the 12 month agreement is completed, they must pay the full amount of the cost of the site if I'd had built it up front, so essentially they're committed for a year, which gives me a relatively guaranteed income stream each month. After the first year, they can choose to remain my client, and I will continue to provide all the services they've grown accustomed to - for a continuing monthly fee.
Generally speaking, as long as their site is bringing them new leads (business), and stays on top in the SERP, I've found the clients to be very happy with this model.
Does it cost them more in the long-run compared to having a site built turn-key and then paying for updates at an hourly rate (assuming they can't do it themselves.) Possibly. I guess it depends on how often they do updates, and how much they pay up front. But I find it a LOT easier to sell someone on the idea of getting a website for $100-$150 a month than paying $2000-$3000 (or more) up front, because the sites usually end up paying for themselves in terms of the business they generate for people. And when you're dealing with people who aren't internet/website savvy (probably 50% of the population), even if you built them a Wordpress site, they'd be lost trying to make updates. Smart business owners, even if they do know how to handle a CMS, don't even want to be bothered. They'd rather focus on running their business, and making money at what they are best at.
Really, it's not much different from the model the Yellow Pages used for decades. They'd create your ad, and you'd pay an additional fee each month on top of your phone bill. Except websites are dynamic, and are changed and updated often, whereas you Yellow Page ad you were stuck with until the new phone book was printed (and heaven help you if your phone book ad had a mistake.)