The default notification scheme for JIRA will be changed. You will no longer get a notification when an issue is created. Some active projects would send out many emails to large numbers of people whenver a new issue was created. The result is that people would ignore all emails from JIRA. To solve this JIRA will no longer send an email to all people associated with a project when an issue is created. However, you will still get emails when an issue is assigned to you, you created an issue, or if you watch an issue.
It is recommended to use a more flexible system of filters and notifications/subscriptions instead. For a good description on how to use this see http://blogs.atlassian.com/2013/05/bulk-watch-meet-the-new-jira/.
For example, I have created a filter for all projects that I'm interested when a task is created in the last hour ((project = SEAD OR project = BD) AND created >= -1h ORDER BY created). Once I have this filter I can subscribe to it and get notified by email when something happens. When creating the notification you can specify how often to send the email (make sure it is the same duration as the created above). In this case I will use advanced and specify it using 0 0 * * * ? * for the advanced option.
Feel free to leave comments here with more filters and other ways to get notification.