Are you taking into account that people have one and possibly even all of the following devices?  iPhones, iPads, and Computers.  If so, you need to see for yourself what your site looks like on them.

I just looked at my site on my new iPad2 (woot woot) and found out that my formatted table columns at width 600 pixels needed to be changed to 100%, along with the square images being brought from 200 pixels down to 150 pixels for them to fit properly.

In order for the site to load nicely on the iPhone there is a plugin for WordPress called WPTouch found here.

At the present moment Skype for iPad is just an iPhone version enlarged 2x and then pixelated.  It bugs me.  Skype: Do Something!

Mint.com is supposed to have a beautiful little gadget for iPhone, but for the iPad: No such luck.  Get with it!

Some items I have found for the iPad that I am really enjoying are listed in an article here.

Back to my original thesis, designers need to concern themselves with every and all gadgets out there.  We used to be concerned mostly with one browser to the next, one operating system to the next, but now we are concerned with all sorts of viewing sizes.  The main ones are the smart-phones, the tablets, and the notebooks, aka – the 3:1