THere's a lot to be said about the Cambrian Exlosion, but I suspect that the figure of 41 phyla is based on the out of date analysis - at the time Gould wrote _Wonderful Life_ many specimens were thought to represent extinct phyla. More recent analysis has revealed otherwise - that although strange to our eyes they fit very well into the phyla that were already known.
Some other points to consider : The fossil record from Chengjiang - as well as the related fossils found at Sirius Passet and the Burgess Shale are exceptional. The fossil record rarely preserves soft-bodied life and failing to take this into account exaggerates the problem.
Trace fossils from earlier metazoan life have been found, from well before the Cambrian explosion. This report from last year shows a fossil worm trail from rocks that are 1.2 billion years old. That would allow not tens, but hundreds of millions of years from animal life to evolve to the level we see in the Cambrian. To put it in perspective there is more time between that fossil and the start of the Cambrian than between the start of the Cambrian and us.
http://news.bbc.co.uk/1/hi/sci/tech/1977935.stm
The "molecular clock" evidence also points to an earlier divergence.
To put it most simply, while there may have been a genuinely rapid diversification much of the problem is down to the limits of the fossil record.