Is there any way to get apps I got off Installous onto my non-jailbroken iphone?

Could I change the .ipa to a .app or is there a way to install AppSync 4.x directly onto my iphone? I don't want to jailbreak it, but is there a really easy way to jailbreak it, like jailbreakme.com? My iPhone is at Version 4.1, if it changes things.
I already have a jailbroken iPod Touch, and the reason I jailbroke it was because the warranty expired. I just got my iPhone yesterday, so I don't really want to risk having the warranty voided, but I can't play a lot of my apps.
 
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