Sony do sometimes send out mandatory updates - you can't go online with your PS3 unless you install the patch first. Other than that, there's nothing in any of the upcoming patches that sound nice enough to bother updating frankly.
Well the older phat variants are probably more prone to failure at any given point than the new ones. Sheer chance suggests some phat PS3's are going to give up the ghost just after running a firmware update. It's a common human failing actually - we assume because two things that have some connection happen together there must be a causal link between them, when in fact it's just that two things with a certain likelihood randomly just happen to coincide.
You do get updates that are broken/badly coded that cause problems occasionally. Both the 360 and the PS3 have had them in the past but they usually get withdrawn and fixed pretty damn quickly. Most of the time, your console going pop just after a patch is coincidence - it'd probably have gone pop that day anyway, whether the patch was installed or not.
Jon