If you are hosted on a standard Joyent Accelerator (e.g., if you have an Accelerator ID of 'z12345AA'), many of the features described here will be missing or will look different. You should refer to the Joyent Accelerators Knowledge Base instead.
Similarly, this knowledge base does not apply to Joyent Shared Accelerators (one of these hosts you want to refer to the Shared Accelerator Knowledge Base.
You have root access so you are able to install almost anything (providing you do not violate the AUP).
The baseline deployment options on these accelerators are:
You can send email from your Accelerator using sendmail (/opt/local/bin/sendmail) or by connecting to the SMTP server on 127.0.0.1:25. You are restricted to sending email to 500 recipients per hour. You are not able to receive any email with the out-of-box configuration, though all of the parts are there (postfix, courier) for you to configure on your own if you so desire.
MySQL is up and running on your delivered Facebook Accelerator. Your welcome email contains the root password for your database.