Tip n Tell indicators are seen on plasmas that are shipped because plasma displays are much more fragile if they are shipped flat. It's like shipping a piece of glass flat as opposed to on edge. Glass on edge is much stronger then glass lying flat. Not all plasmas have these indicators. I saw mine come straight to the distributor from Japan and it did not have any indicators on it and it's a 50" unit. They are put on by retailers that have to ship the devices through common carriers.
The Tip N Tell indicators may indicate whether the device was dropped, shipped on it's side or otherwise tilted. If one is set off, it doesn't mean the device is garbage. It just means that one needs to be careful when opening it and it's better to do a through inspection. If they are not set off, there's a good chance the unit is fine but it's always worth checking and plugging in the device while the delivery person is there.
However, plasmas can be tipped for such things as configuration purposes but I don't think anyone recommends mounting it on your ceiling. I dunno what Philips was thinking

My plasma owners manual tells me to put it flat on the ground to install an optional interface card. It'd be pretty hard to install it while mounted on the wall otherwise.
Hope this helps,
Santo