As has been said above, you'd have to approach this from a long-ball investor's POV... As my interest in this area lies only in commodities, I'd have to sort of half-lean on the fence and the first half of 2009 may differ greatly from the second, or it may not. Essentially there will be a rebound at some point; whether it is the second half of this year or 2010 depends on how quickly the powers that be can stimulate the economy. Personally I lean more towards 2010, I just don't see us stopping the rot in the next 6 months, but people more knowledgable than I have are slightly more optimistic. Anyway here goes...
Crude will hover in Q1 & Q2, due to decreased global demand and the fact that OPEC are happy to support the lower pricing in order to stimulate demand for Q3/Q4. Various analysts have wildly differing forecasts for oil prices in the second half of 2009; OPEC could decide to cut production further or we could see an (IMO unlikely) rebound of manufacturing in the summer; with that in mind we could see a return to three figures a barrel at almost any point in the next 2 years.
With metals, copper and iron ore are obviously affected by the death of manufacturing; I have the feeling it could be 2010 before we see any discernible turnaround here, but as production is reduced by the likes of Rio Tinto and Freeport, the price will likely stabilise later in the year. As more people become more worried in the short term about deflation, gold and silver will likely see a downward blip in deamand. This is obviously a pretty explosive topic at the moment, no-one is really prepared to step forward and predict what is going to happen but if I were a betting man (and I am) I would expect inflation to hit us pretty hard in the coming 18 months.
To summarise, I will be watching the commodities markets very carefully in the coming 3 months, with a view to catching a pretty decent surge in oil and gold prices, with a decent recovery of copper and ore to come in the 12-18 months after that. Of course, I am incredibly experienced and could be laughably wrong; but better to express and opinion and be wrong than merely regurgitate the musings of others (cough-Peston-cough...)
SL