You can load .pdf files on your iPhone .. you can load with downloading pdf viewer from the installer and put the file to /var/root/Media/PDF/ and then the .pdf file will be visible in the pdf viewer and you can read it .. look at the pictures ... its very simple using ibrickr .
And again tnx MacManPro !
If you have the phone jailbroken and you have SSH installed, you can use SSH to copy the files over to your phone. You can use WinSCP if you are using Windows and Fugu or CyberDuck if you are using a Mac.
All I do is email the file to myself. or if you have adobe acrobat standard, (ability to create your own pdf's) or ecopy desktop ( another great pdf editor porgram) you can save them as an html file and upload it to your google docs account (must have a google account). If you need me to convert a file to PDF, just PM me. I can even convert it to an html file for you.