More and more mobile phone owners use the Internet browsers on their phones. iPhone and various different platforms that have sprouted contributed to the development of mobile phone browsers which required a special attention from web designers. Web design for PC viewing is clearly not the same thing as design for mobile phone browsers. This is why site owners are adding some emphasis on mobile web design versions of their site.
However, a website's mobile version is not that simple, as mobile phone screens do not offer the same amount of pixels as a PC monitor. Web designers must ensure that page requests from mobiles will receive the most essential information. You also have to take into account load time and standards compliant web design.
The big question for each site owner that wants to redo his site's mobile version is the following one: "What will the users of my site do when accessing it through a mobile device?". The first thing the site owner should have in mind is to meet his users' needs really quickly. People accessing websites from their mobile phones are more likely to need rapid information that suits them for the moment.
A good example of this would be comparing the two versions of Flickr. Both versions have, more or less, the same content on the page, but the hierarchy changes for the smaller screen. They also appear to be taking into account the fact that most people probably are not going there just to browse images as much as they are visiting mobile to manage their account or access certain information.
Considering screen real estate is very limited, you should only show the essential of your site. Mobile phone users should absolutely be able to make selections really easily, as entering text on a mobile phone can be really tough, especially for someone who's in a hurry or who wants to find the needed information really fast.
Web design industry is continuously changing and adapting to the needs of website users. Accessing websites via phones and mobile devices became more and more popular, which requires a strategic approach from the web designer.
Remember that content is still the king and people are going to your site, mobile or otherwise, to access the information they need. That's why you should always think twice about how you want your content to be delivered and you will be one step ahead in the mobile web design game.