Is random.expovariate equivalent to a Poisson Process
On a strict reading of your question, yes, that is what random.expovariate does.  
expovariate gives you random floating point numbers, exponentially distributed.  In a Poisson process the size of the interval between consecutive events is exponential.  
However, there are two other ways I could imagine modelling poisson processes

Just generate random numbers, uniformly distributed and sort them.
Generate integers which have a Poisson distribution (i.e. they are distributed like the number of events within a fixed interval in a Poisson process).  Use numpy.random.poisson to do this.

Of course all three things are quite different.  The right choice depends on your application.
I read somewhere that the python library function random.expovariate produces intervals equivalent to Poisson Process events.
Is that really the case or should I impose some other function on the results?