Yep, and Firefox doesn't abide by all of the W3C standards.
I have heard this bandied about quite a bit, but haven't seen much evidence of it, other than some minor bits of CSS tomfoolery.
Now I'm sure it's important for those people that are actually using those bits, but if they are irritated at Mozilla for such things I imagine they must be outraged at Microsoft for the regular disregarding of standards that are much more mainstream.
Yet you haven't mentioned that, which leads me to wonder about your motivation.
I have firefox and Mozilla.
I find myself going back to Mozilla a lot. It has more options and better cookie management. I take it Firefox is kind of like the trimmed down version of Mozilla. It seems more for the person who does not like too many dials on the dashboard.
There options control is minimal. I have yet to hear anyone list the advantages of FireFox over Mozilla other than it has a smaller file size, but Mozilla also includes Mail.
If anyone could list the real advanages of Firefox over Mozilla then I would apreciated it. Of course they are both put out by Mozilla.