I’ve seen an influx of websites that put all of their content on one page, ala this site. Even the sites on some of the lists I see in Smashing Magazine do this (like this one, with what seems like a hundred sites, the majority of which use it).
As a programmer, this style bugs me (for a number of reasons, mostly technical, not the least of which including maintenance, SEO, loading times, etc.), but more importantly, I’m curious as to why it became popular among designers to begin with?
There are two separate trends involved.
The first is the trend to have a simple site. If it’s a brochure site, then it likely doesn’t need four separate pages. One scrolling page is easier to use, navigate, and maintain. A lot of iPhone app sites use this model. As do a lot of small businesses. A lot of sites can benefit from this.
The other trend is Flash developers finally discovering HTML, jQuery and AJAX and still thinking inside the old Flash model of ‘one file = one site’. This is different than the first trend in that this is a large site with lots of content compressed into one page of data/interaction. As you state, this method has all sorts of drawbacks, though they are surmountable with the right code (making sure URLs change/are bookmarkable, Google can navigate the content, load times are managed via AJAX, etc.).