LogoMe is a new application available in Cydia that will change your boot logo without having to rejailbreak or restore. All you need to do is installing the application, launching it and typing in the URL where the photo can be downloaded from (that means that your photo has to be somewhere online – ie. Flickr). You will not be able to change your boot logo by using a photo from the library.
Once you’ve typed in the location URL, tap “Download” and LogoMe will download the file. After having downloaded it, you’ll be able to preview your boot logo. When I previewed mine, it showed a white bar at the top but I decided to install anyway. When you’re done, reboot your iPhone and you should see your new custom logo. Note that the white bat doesn’t show on my custom boot logo anymore once installed.