You can put this in the "why would you want to do that, oh well it's cool to say I can" bucket. ModMyi.com user ismoothproject
has built an Apple Script app which will take iPad-only apps you've purchased (still requires a purchase - this isn't warez, folks) and allow them to be launched on an iPhone, as well as transfer them to your iPhone wirelessly. It requires a jailbroken iPhone, as it sends the .app file via SFTP (requires OpenSSH be installed on your device). Not all apps work, as they're not really meant to be on that device obviously, but like I said - this is more just "oh, weird, why not?"
This isn't entirely new - in May of last year we posted
info on how to port the (then iPad only) Netflix.app to your iPhone. This user's method is essentially the same, and can be done manually as well. All he does is change the app's permissions to 755, as well as the binary. Then toss the .app in your iPhone's /Applications folder, and respring. Voila, iPad app on your iPhone, working kinda sorta.
If you have a need to do this, and do not want to do the manual method, you can use ismoothproject's instructions:
1. Download iTelePad2Pod Here
2. Unzip iTelePad2Pod.zip
3. Move the iTelePad2Pod folder to the /Applications Folder on your Mac.
4. Go to the moved iTelePad2Pod folder (/Applications/iTelePad2Pod) and open the iTelePad2Pod application.(/Applications/iTelePad2Pod/iTelePad2Pod.app)
5. Follow instructions in the app.
He's also got a YouTube video:
[ame=http://www.youtube.com/watch?v=a_7kcyrV2Tk]YouTube - How To Run iPad Apps on your iPhone or iPod Touch Tutorial iTelePad2Pod[/ame]