Having bashed philosophy a bit, time for a slightly different viewpoint.
Dawkins (who should probably stay away from Twitter) tweeted:
Philosophers' historic failure to anticipate Darwin is a severe indictment of philosophy. Happy Darwin Day!
— Richard Dawkins (@RichardDawkins) February 12, 2014I think there's a couple of things going on here. One is the historical trend which has separated "philosophy" from "science". Some philosophers, but only a few scientists that I've seen, seem to be fighting against this trend and trying to reclaim the position that science is a branch of philosophy.
This may be true in a weak sense, but it doesn't sit well with many given what seems (from my outsider viewpoint) to be the current state of philosophy as an academic subject. Even discounting philosophy of religion, there have been a number of cases recently of philosophers making poorly-informed excursions into scientific fields (obligatory XKCD), including Nagel's recent book and Fodor and Piattelli-Palmarini on evolution. Add in the religious philosophers, and anyone else who wants to do metaphysics in ways not grounded in evidence, and it's not really surprising that some scientists find philosophy objectionable.
So Dawkins' tweet could be taken as a jab at the sort of philosopher who thinks they can sit in an armchair and deduce the entire universe (or at least important parts of it) from first principles; other philosophers might call that a strawman depiction of philosophy, but it might be better to call it a noncentral depiction. But as stated, it's nonsense; it is not reasonable for a scientist to indict the whole field of philosophy for failing to do something that most philosophers, and all scientists, don't regard as within its remit.
On the other hand, many philosophers have castigated Dawkins as "philosophically naïve" for the way he (for example) brushes off traditional philosophical arguments about religion. This is equally unfair; as discussed in the Plantinga posts, we have no reason to take such arguments seriously.
Another fault on the science-as-philosophy side is the fact that every time this comes up someone makes the argument from historical word usage: what we now call "science" used to be called "natural philosophy". This is totally irrelevant to the question of how we should regard science now; in fact, the change in terminology is almost certainly caused by the fact that the majority practices of science and philosophy diverged sufficiently that it no longer seemed appropriate to call them the same thing. Science has become its own thing, whether you regard it as a sub-cluster within philosophy or as a noncentral outgrowth of philosophy, and it's unlikely that this will change. Arguing over names is pointless.
So is philosophy worthless? Of course not, the only worthless part is the metaphysical-verbal-reasoning nonsense (plus some inevitable lunatic-fringe in each subfield). Plenty of scope for important work in epistemology, ethics, meta-study of individual fields (e.g. philosophy of science, etc.), even metaphysics. Then there's the whole issue of personal philosophy as distinct from academic philosophy.