Do sites need to integrate mobile platform for increasing number of mobile users?

I am not sure if this is the best place to ask this but since its site administration, I suppose there is no harm asking it here.

There is obviously a big growth in mobile users on various platforms such as smart phones, iPad, Android based devices, etc; I was wondering therefore should sites be catered to these users or can they access the as they are, which are obviously in most cases designed to be accessed on standard platforms such as PCs?

 

I have a substantial % or mobile users on my site
many years ago most mobiles needed wap sites
now most mobiles have a small regular browser displaying ALL HMTL / XHTML pages
however since the browsers included in mobiles ( Nokia ) are much smaller in size, they also have NO or less error-tolerance built in
means
you need VALID html / xhtml pages to assure mobile users see the page properly rendered

the very newest mobiles - such as my N900 - no longer need any special mobile page
N900 and other top end mobiles have high resolution screens and show a full page on screen with limited vertical scrolling needed

I would never invest money to make my pages back compatible to OLD mobiles
the mobile market is dynamic and for example here in the PH, most ppl upgrade mobiles frequently
rarely someone uses a mobile older than 2-3 years among those going www with a mobile

I test my site - all parts - using my N900 and all looks perfect just by using validated pages ( valid CSS / valid HTML ). before I had a N95 and did the testing with the much smaller screen resolution = still fine.

fortunately professional web publishers used valid / validated pages since many years. hence no real change needed in the age of high resolution mobiles. the time of WAP pages is history.

 

Thanks for explaining that. Yeah, I have an iPad and I can access the sites as normal on the iPad as I would on a PC.

So, why are companies like Google, Apple investing in mobile ads?