We currently do not support recurring tasks. However, we probably will do so in the future.
For birthday reminders and similar annual events you can use Dates when editing or creating a new person. Data that you enter here will be send to you a week before in your weekly e-mail summary. You will also find the pending data in the right column of the CRM Home (status).
You can also subscribe to a crm calendar with your Outlook, Apple or Gmail calendar to get your reminder there.