One of the features coming to iOS 5 this fall spruces up the Messages app by adding contact photos directly to text messages. A chat in progress, especially with group messaging where multiple people are involved, is much easier to follow with everyone's picture displayed.
To get this feature now, you must jailbreak your iPhone to install the Cydia app store. Open Cydia and navigate to Sections -> Tweaks to find the app called ChatPic, or search directly for the title using the search function.
ChatPic costs $0.99 and can be purchased directly using the Cydia app store. Payments from PayPal and Amazon Payments accounts are both accepted. Once installed, no new home screen icons will appear and there are no options under settings to configure. ChatPic only works with the default Apple Messages app that comes with iOS for text and MMS messaging.
Photos from your contacts list will appear next to incoming messages just like they will in iOS 5. Many Android devices also support this feature, which makes it more intuitive to keep track of who's sending messages. Add more character to your text messages with ChatPic, without having to wait for the release of iOS 5.