It's happening again. The FAO warns that food prices are rapidly approaching their 2008 peak. In particular, they predict that food import bills will pass the trillion dollar mark last reached in 2008, with poor-country imports contributing a significant proportion of this.
Dani Rodrik points out that high food prices can be good for farmer-producers. Poor rural people sometimes benefit from higher prices for their produce. This assumes that markets are somewhat efficient and, as Oxfam points out in response, that producers are not also consumers. It also leads to the conundrum where farmers attracted to higher prices focus on producing high-price goods (Sugar is at a 30-year high, for example) instead of staple foods and cereals (maize prices are plummeting in, SA at least, after a recent bumper season).
Rising food prices are particularly bad for the urban poor, who often do not have access to land to produce their own small crops and fill the gaps. This is where food riots broke out in many countries the last time around. Recent "bread riots" in Mozambique clearly show that poor communities haven't lost the ability to riot if their food source is threatened. Investment in poor-country agriculture is beginning to happen (for example to help mitigate the impact of climate change) but this will not help soon enough to prevent the food security of millions being threatened by price-rises in the next few months.