If you are purchasing apps or music, you can pause downloads to wait until you have a faster connection available, something that is particularly useful if you’re downloading games or albums which generally take up more bandwidth than apps and single MP3s. To pause a download, simply tap and hold and choose Pause from the contextual menu.
Staying with the Marketplace, your Windows Phone will alert you as to when an update is available for any of your apps. Sometimes, however, network connectivity issues will prevent download, but you can retry the download with a tap and hold, and then select Retry.