Nitrous.IO doesn't provide sudo access as of Jan 2014. We suggest that you add any packages you require to our autoparts package manager library:
https://github.com/nitrous-io/autoparts
If you need help writing a package, you can get in touch with the team by writing hello at nitrous dot io.
What types of packages are you looking for though? We have package support for MySql, Postgres, Redis, Memcached, and many other services, languages and databases.
[EDIT APRIL 2015]
We just announced the next generation of Nitrous that supports root access on your own dedicated cloud VMs. Learn more here: