Staffan said:
I'm pretty sure Abundant Step and possibly Wholeness of Body were spell-like in 3.0, though.
from the 3.5 SRD on the concentration skill...
"You must make a Concentration check whenever you might potentially be distracted (by taking damage, by harsh weather, and so on) while engaged in some action that requires your full attention. Such actions include casting a spell, concentrating on an active spell, directing a spell, using a spell-like ability, or using a skill that would provoke an attack of opportunity.
In general, if an action wouldn't normally provoke an attack of opportunity, you need not make a Concentration check to avoid being distracted."
That last sentence pretty much covers when you wont need to make a concentration check.
From that a Gm can infer you will need to make one for interruptions fromAoOs for those other things. Its clear that it applies to skills but what other things?
For instance...
Get up from prone draws an AoO. if it hits you, you need to check to see if you get up.
heck, if taken even a little further, rushing a guy with reach provokes an AoO. if you are hit, you need to make a check to see if you continue.