What are these cream plastic-like blobs on my circuit board?
I've read @Matt's answer.  The adhesive for holding the components during reflow is usually red in color, it's less runny, and there's usually less of it.  Here's an example of such adhesive.   

I've got a different hypothesis.  I would guess that this is a thermally conductive adhesive that's holding something on the other side of the PCB.  It may be improving the thermal conductivity between the PCB and the heat sink (or case).  Notice that this white adhesive occurs mostly around components which are heat-sunk to the PCB.