I'm with CF. If I'm woken (as I often am by a snoring husband) I have no trouble recalling the dream. I also share Veles' experience. If I sleep in, I'm much more likely to have more detailed recall and, on top of that, more likely to lucid dream.

If I'm mentally very busy before bed time, my recall is compromised. If I go to bed at a reasonable hour and raise energy and meditate my recall is significantly better. I've noticed too that there's often a correlation between how strong the energy sensations are and how good the recall is.

The exception occurs occasionally where I suddenly get a night of scant recall or none at all for no apparent reason. A few times that this has happened, one friend or another will tell me I popped in for a visit.

I agree with this bit, BloodyShade,

I've noticed that to keep the dream information longer, you need to take a few minutes thinking about the information contained in this 'ram memory'. It'll be placed in a part of memory that will last longer, you'll then have more time to write it in case you keep a dream journal.
You will probably find that the longer you keep your journal, the better your recall will become.