Yes, many of his jokes were biting and took specific shots at people. And were mean spirited. And I'd be willing to bet he won't be asked back. But if you take a step back and look at it, the jokes were funny. And while many people in the audience (you know, celebrities) didn't enjoy it, I bet the viewing audience sitting at him found it funny.
Bad taste is very subjective. What may be in bad taste to you might be perfectly fine to me. I understand with such a large audience you have to walk a much finer line than you would in a comedy club. But I think that's why Gervais went after the celebrities so much. Easy targets who might get mad, but at the end of the day drive home in their solid gold cars. Sure Tim Allen looked visibly ticked off, but it was a funny line, and no one gets hurt by it other than Tim Allen. And hopefully Tim Allen has a big enough sense of humor that he'll get over it. And if he doesn't, he still has that solid gold car.
Celebrities, for the most part, take themselves way too seriously. You saw some of that behavior last night. If only they understood that's why they make such easy targets.