As of April 1st, 2015, both Lyft and Uber "ride sharing" services are allowed to pickup arriving passengers from the Indianapolis International Airport pickup location which is located in the ground transportation area.
When your plane disembarks, you will need to pickup your luggage (if you have any) at the baggage claim area downstairs.
Then go outside to the passenger arrival lanes and walk across to the ground transportation area, attached to the parking garage.
Go through the two sets of double doors and look for your Uber or Lyft driver on the far side of the pickup lanes.
Note: Although the Lyft website states the normal arrival lanes as the pickup location, according to airport authorities, you MUST proceed to the ground transportation pickup lanes for your ride.
See the image below for more information: