From the license for Juno:
2.5. You expressly permit and authorize Juno to (i) download to your computer one or more pieces of software (the "Computational Software") designed to perform computations, which may be unrelated to the operation of the Service, on behalf of Juno (or on behalf of such third parties as may be authorized by Juno, subject to the Privacy Statement), (ii) run the Computational Software on your computer to perform and store the results of such computations, and (iii) upload such results to Juno's central computers during a subsequent connection, whether initiated by you in the course of using the Service or by the Computational Software as further described below. In connection with downloading and running the Computational Software, Juno may require you to leave your computer turned on at all times, and may replace the "screen saver" software that runs on your computer while the computer is turned on but you are not using it. The screen saver software installed by Juno, which may display advertisements or other images chosen by Juno, is an integral part of the Computational Software and you agree not to take any action to disable or interfere with the operation of either the screen saver software or any other component of the Computational Software. Juno may set different requirements for different subscribers with respect to the Computational Software (including without limitation whether use of the Computational Software is required and the volume of computations required to be performed) depending on service level or other factors we determine. You agree that, as between you and Juno, you shall be responsible for any costs or expenses resulting from the continuous operation of your computer, including without limitation any associated charges for electricity, and that you shall have sole responsibility for any maintenance or technical issues that might result from such continuous operation. You agree that, as between you and Juno, Juno shall have sole rights to the results of any computations performed by the Computational Software, including without limitation any revenues or intellectual property generated directly or indirectly as a result of such computations, without further compensation to you. If your usage of the Service is infrequent, Juno's ability to obtain the results of completed computations may be impaired. Consequently, you expressly permit and authorize Juno to initiate a telephone connection from your computer to Juno's central computers using a dial-in telephone number you have previously selected for accessing the Service; Juno agrees that it shall exercise such right only to the extent necessary, as determined in Juno's sole discretion, to upload the results of completed computations to Juno in a timely fashion; and you agree that, as between you and Juno, you shall be responsible for any costs and expenses (including without limitation any applicable telephone charges) resulting from the foregoing...
So.... If you use Juno and turn off you computer or unhook it from the Internet, you're in violation of your EULA... Also, they can change your screen saver, and you can't change it. By the way, if you don't use it enough, you might randomly connect to the service... Why do these freakin' things have to be so restrictive (sorry this was so long, I didn't want to be accused of taking it out of context)...