The MAP signal does fluctuate and is particularly noticable once you get onto boost. This is because the MAP sensor is fast enough to detect fluctuation within the manifold. The air flow and pressure within a manifold is not constant due to the opening and closing of valves, turbo fluctuations etc. The UTEC uses a short averaged MAP for load points but the data in the loggers is the faster reacting MAP signal.
The faster data was primarily used by us for analysing boost controller performance.
Boost gauges generally provide an averaged reading however some gauges will show a vibrating needle indicating a pulsating pressure within the manifold.
For the next revision of software we have used a longer averaged MAP signal for various functions including the loggers. The loggers will then produce a "smooth" MAP curve similiar to that displayed on your boost gauge.