I've been trying to develop Mobile web lately either Iphone or Ipad. And i found out that iphone website development is easy since you just need to re size the screen in Safari is you want get a quick preview what its looks like on Iphone.
I search through and a bit stuck for testing Ipad website design since i don't have the Ipad.

Here is my solution for someone don't have an ipad, working on windows and want an Ipad simulator for windows.
First download the source code from http://ipadpeek.com/ which i found that it's work great.
Extract all ZIP file, and open the script.js

Change the First file below

var setFrameUrl = function(url) {
  if (!url || url == 'undefined') return;
  if (!url.match('^https?://')) {
    url = 'http://' + url;
  }
  $('#url').val(url);
  $('#frame').attr('src',url);
};

into

var setFrameUrl = function(url) {
  if (!url || url == 'undefined') return;
  if (!url.match('^https?://')) {
    url = '' + url; //delete the front to make it work on local
  }
  $('#url').val(url);
  $('#frame').attr('src',url);
};

Basicly just remove the http:// to make it work on local.

now you can simply paste your local URL for example

file:///C:/Users/yourname/Desktop/mywebdevelopment/index.html

into the index.html of the ipadpeek

or if you work on localhost you can do the same thing.

And i found another that works just the same from electric plum.
here's the download link http://code.google.com/p/ibbdemo2/downloads/detail?name=iBBDemo2.air&can=4&q=
This one is a simulator of both iphone and ipad, and can work on local as well.

Hope it will help.