Caffeine does indirectly promote release of acetylcholine (along with the monoamines, dopamine, serotonin, norepinephrine) via antagonism of adenosine receptors.

I've heard anecdotal evidence on caffeine giving people nightmares and vivid dreams, especially when consumed immediately before sleep.

After digging a little more, I also found that caffeine is also an acetylcholinesterase inhibitor (it disrupts the enzyme that breaks down acetylcholine) which have medical use in promoting REM sleep and induce lucid dreaming.