Thanks everyone for the kind words!
I admit I also thought it looked like a disco after I set up the LED strips last night and wondered what people in the streets were thinking when they looked up at my apartment. :)
So I decided not to drill any holes into the concrete ceiling and instead decided to stick the LED strips to the ceiling with double-sided tape and some kind of aluminum profile, as suggested by a few people on this + the Brazilian CP forum, and by my friend Steve Davis (who helped set up the Ping wall and who I met up with today at the BACPS Annual Show and Sale - which had some beautiful CPs!).
Leaving the BACPS show, I stopped by a Home Depot and bought two 48 inch aluminum profiles similar to the ones in this link, except one side was narrower than the other (it had an L shape):http://www.homedepot...n&storeId=10051
I also bought 2-sided tape that can supposedly hold 5 pounds:
I first folded regular masking tape into two 48" long sticky cylinders and placed each of these inside on of the "L" aluminum profiles, against the right angle. Over this, I placed the 2-sided tape, so that it would be facing +- 45 degrees from either surface of the "L" profile. Then I stuck the LED strip to this tape. Last, I put another strip of two sided tape on the outside of the broad side of the "L" profile and stuck this to the ceiling. Here are both already in place (sorry, i forgot to take pictures as I put this together):
As you can see from the pics above and the one below, I still needed to figure out what to do with the cables and transformer dangling from the ceiling.
So I basically taped the cables to the ceiling itself, using the tape that was actually protruding from the "L" profile:
Then I stuck the long cable to the wall:
As you can see, they are almost completely hidden by the blinds, thus very discrete:
Now I just have to add a timer, decide how many hours to leave the lights on every day, and wait for the Pings to flourish! :) Several of the leaves I "planted" on the Ping wall are already beginning to form young buds.
Wish me luck!
P.S. Adam, the LEDs do seem to get a little hot, but nothing that made it uncomfortable to hold in my hand.