If you have a Mac (which you probably want if you are going to do any iPad development) -- the Mac comes with Apache already installed -- you just have to turn in on, step by step instruction here:
http://oreilly.com/pub/ct/49[
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If you want Apache + PHP, then that's there to:
http://www.phpied.com/installing-php-and-apache-on-mac-osx-that-was-pretty-easy/[
^]
You can use that to serve as your web host over your local WiFi for testing and development.
Depends on what equipment you have, and what sort of environment you want to write the host side in, but you can essentially do the same thing with a pc (I don't have a handy link for that, but if you Google there are probably plenty of tutorials).
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