I noticed the same thing. People getting email notifications and acceptances. I found on their website under "After You Apply" the following statement: "When a final Graduate School decision has been made you will receive an email notice to inform you that your decision letter is available to view online. You can view the letter through the 'Check application status’ section of your Application Supplemental Form (ASF).
An official copy will also be sent to the address listed on your Graduate application. If the program to which you have applied does not require you to complete an ASF then you will not be able to view your letter online. The following programs currently do not require the ASF: Non-Degree applications, MBA or MS applications offered by the Robert H. Smith School of Business, and selected applications for a master’s or certificate of professional studies."
So I guess we'll probably get an email to check online as well as something in the mail.