At least the back of your iPhone 4 can look like a communicator. The folks at Cafe Press have a variety of iPhone 4 cases that are designed in the style of the communicators used throughout the various iterations of the series and movies. Some of the cases are silicone, and others are slider cases. Each case costs $25. Check out the styles available at the Star Trek Communicators Gifts page.
Some of our links in posts like this one are affiliate links, which means that we may receive a small commission on purchases at no cost to you.