I just read some fantastic articles from Elizabeth Pantley and there is actually one specific one about dropping the second nap - see http://www.pantley.com/files/NAP1%20Shifting%20schedules%20from%20Two%20Naps%20to%20One.doc
You can download all the parenting articles here - http://www.pantley.com/elizabeth/links/4.html
Zoey dropped her second nap *really* early, at around 10 months - it was scary, she'd stay up for 7 hours before needing to sleep i.e. getting really cranky! It took a couple of weeks to settle into a routine of one nap a day, and in fact, she still sometimes has a second nap now, at 12 months of age, though very rarely (usually when she did not sleep well the night before, or if she's sick).
I remember it being very difficult in that transition period, because some days she'd push her morning nap later and later so it was actually a very early afternoon nap. The problem was, if she needed a second nap, it was just waaay too late (after 5pm), which would interfere with bedtime. She just could not make it, so then bedtime would be pushed to after 9pm and then the vicious circle began. It made getting out really difficult, as there was no way to predict when a nap would be needed (and she really slept better at home). The way it worked out for us - it was December holidays, so with my husband off of work, we just stayed at home and we followed Zoey's cues but made sure she went down for a nap by noon and was up by 2pm (so roughly 5 hours awake time either side of the nap); in two weeks, she had settled in to the one nap a day routine.
Read the articles above for some really useful tips - I wish I'd found them back in December!
