If you want to learn how to best look after your battery in ANY device you own, look here and have a read....
http://batteryuniversity.com/
90% of people on here speculate, guess or go off of something they read in a manual that one time 5 years ago. Go have a read of that website if you want proper, acurate information.
Classic example is mikezmac. He is recommending you discharge as much as possible (over 2 days for example) then recharge only once every other day. This is WORSE for the battery than going lots of partial recharge cycles from say 60% up to 100% each night.
Look at table 2 here....
http://batteryuniversity.com/learn/article/how_to_prolong_lithium_based_batteries
When going through 100% depth discharge cycles you will usually only get about 300-500 cycles out of a Li-Ion battery. However, in comparison when going through 50% depth discharge cycles you get about 1,200-1,500 charge cycles!
To see what the definition of a discharge cycle is, look here...
http://batteryuniversity.com/learn/article/discharge_methods
You will see that simply charging from 60% - 100% does not tend to constitute as 1 cycle. Apple themselves say that if you charge 40% on day 1, then 50% on day 2 and 10% on day 3 that counts as 1 single discharge cycle. Now obviously that is not the whole story, but it is much more accurate than what some people said above, where it was implied that simply charging from 60% to 100% was counted as a discharge cycle, its not, plain and simple.
Temperature when charging also comes into play, there is so much that comes into consideration when chargin batteries.
However to answer your question, yes, it is better to charge from 60%-100% each night, instead of letting it run down to 10% and charging back to 100% every other day.