Yes, leaves often can absorb water through their leaves, and in fact, in some plants it is almost the only means of water uptake. Think about epiphytic bromeliads for example. These have a root system that only serves to anchor the bromeliad against its host tree, but it does not parasitise on the host tree's sap. The bromeliad meets all his moisture requirements for photosynthesis by trapping water with its leaves, and then absorbing it.
How do leaves do this: There are two means. First of all it is important to remember that most leaves have a waxy layer (the cuticle) which is impenetrable to water. However, that layer is interspersed with stomata and trichomes (hairs), which both can take up water. The trichomes are similar in morphology and function as root hairs, so it comes as no surprise that they can indeed absorb water. Through the stomata and trichomes, water can bypass the waxy layer found on most leaves. Please note that water uptake through stomata is much more difficult than the uptake through trichomes, so the latter play a much more important role in water uptake, whereas the stomata play a larger role in gas exchange.
How well a plant can take up water through its leaves will obviously depend for a large part on: how many trichomes and stomata are present on the leaf surface, how efficient they are, humidity levels, temperature, climate, light intensity, leaf age, nutritional status of the plant etc.
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