I don't get why SEF is important, search engines can perfectly index URL's with query strings, avoiding sessions and id variable name. So is this SEF thing a big myth or just something created to sell SEO services?
Even if they did or do carry no direct relation to SERP placement. They're still worth having for the sake of how they look. To the surfer, when displayed in the search results they're another visual indicator that they're going to a page that is relevant to them. Plus, whilst at your site, they are often indicative to the navigational structure of the site. Another bonus is that, in your stats you can easily identify what page you're looking at. You're right, search engines can perfectly index URL's with query strings and google does ignore id=. But I wouldn't be too sure about the session variable. I've had problems with spiders being confused about session variables and spidering for ages over and over the same content. As for whether they help your placement? Well, I'm not 100% sure. But they can be done with a little effort and help in many other areas.
see. u wont have much advantage in changing index.php?f=28 to index/f-28/, but there is an advantage if u use index.pfp?f=28 to something like index/page-title-f-28/ because of the keyword in the url.
nowadays, by SEF most ppl i talk too mean removal of PHP Session IDs. the ones that look like this : page.php?session=3281742389470123470293874982374