BigBoss has written an article on a problem with the App Store/iTunes which also affects Cydia (and will probably also affect Installer 4.0). The problem has to do with installing applications. Have you had a time when you install an app and your iPhone just sits there…there is no icon and you have a spinning wheel next to your carrier icon on your status bar? This has happened to me once and Doug a few times. Though, it is always with App Store apps and never with apps installed via Cydia. Below is what BigBoss has to say about the bug.
There appears to be a major bug in Appstore / iTunes which is a service that is constantly running on the iPhone.I have had many issues with just using AppStore with a lot of apps installed. It takes often 10 or more minutes to try to install. It fails over and over and has to keep retrying. If I log the events using “top”, I can see the iTunesStore binary running with most the CPU in the system and a crash report process constantly coming up. Often times, the phone reboots and takes forever to restart. It seems that deleting some apps helps this work better. I will be looking into this more.
This also seems to affect Cydia and probably will affect Installer 4. Sometimes you install something and find no icon. From what I can see, the above issue occurs during this state. When you install something even from Cydia, the iTunesStore app is again using all the CPU, the phone is running slow, there is a spinner next to the carrier icon, and no icon shows up. If this happens to you, try these steps to resolve it:
1) Uninstall the item(s) that are not showing up in Cydia
2) Reboot the phone
3) Reinstall them in Cydia
Repeat until it works.