Whoa, hold on folks. Bad information being given out based on too-little information from the OP.
First of all, if someone deletes the iPhone *APPLICATION,* that doesn't have the slightest effect whatsoever on the photos. They are stored in a different location.
So no, *based on what little the OP has told us,* he hasn't lost any photos at all.
Second, we can't be sure if he actually deleted iPhoto at all ... or just the icon in the dock. If he actually deleted the application, then yes I agree with McBie ... that wasn't an accident, that took some pretty deliberate doing!
The iPhoto **APPLICATION** can be restored from one's iLife disk, or from the software restore DVD that came with the machine.
The first thing I would have the OP check is whether the folder "iPhoto Library" still exists in the Pictures folder in his Home folder. That's where the photos are, so that's the part that's really important to be sure hasn't gone.
Second, if somehow he HAS thrown out his photos AS WELL as the application, then he'll need to restore from backup ... or if there is no backup, smack himself in the face HARD and then call a professional data recovery service and immediately stop using the computer.
Hopefully the OP will update us on what is really going on, including model of Mac, version of OS, version of iPhoto, etc.