After many years of MPEG2 being the video codec of choice for digital signage it looks as if its days are numbered.
Firstly DPAA (nee OVAB) announce that H264 is the choice for their partners networks (putting to one side the high bit rate they mention), then it turns out that 78% of all web video is now H264 – link here
And a good thing too in my opinion the MPEG-LA licensing fees are a lot less onerous for H264 than MPEG2 for a software vendor enabling cost savings to be passed onto the users of digital signage solutions that support H264 and not MPEG2
Also as many digital signage vendors support Adobe technologies like this and this then of course H264 becomes the obvious choice as like the iPad and iPhone, Flash supports H264.