To answer simply, yes the embedded Rocket server will handle multiple simultaneous requests. However, if you have long-running processes, they may force Rocket to wait until they are finished before responding to additional requests. This is easy to overcome by using Python's multiprocess module. For example, I have a script to batch insert a bunch of records into the database. The script takes about a minute to run and is started by an ajax call. So in web2py, I created a scripts.py module and imports multiprocessing, then subclasses the Process class.
When the ajax call comes in, web2py instantiates my script module, then calls run() to start a new process that does all the work. The moment that run() is called, execution continues so that other incoming requests can be handled and the script runs in the background. Just for fun, I also made my script report progress so that another ajax call could get the status of it.
