SQL injections with noSQL databases?
Generally, with MongoDB we are not building queries from strings, so traditional SQL Injection attacks are not a problem.
There are other issues to be aware of, so it's worth giving that page a read.
The documentation is wrong, In PHP you need to be careful of null-byte injection attacks (http://www.idontplaydarts.com/2011/02/mongodb-null-byte-injection-attacks/) as well as object injection (http://www.idontplaydarts.com/2010/07/mongodb-is-vulnerable-to-sql-injection-in-php-at-least/)