The 30PF9975 has no digital inputs, only component, so I feel it may not conform to the 'HD ready' badge as it is displayed on most of the latest screens. It is able to handle 1080i through component, although personally I've never been able to achieve this with a PAL 1080i signal (from an Samsung HD-745 upscaling DVD player). I think this may have something to do with the 'pseudo' nature of the upscaled signal, but others may be able to give you a definitive answer on this. Several reviews of the set did successfully test it with 1080i from NTSC D-VHS.
The 30PF9975 can't handle 720p through component, but can display the PC resolution of 1280 x 768 via VGA allowing you to play WMV-HD, DIVX HD etc.
According to reports the first generation of Sky HD boxes will include component outputs. However it appears to be unclear what percentage of Sky's programming will actually be broadcast in 1080i as opposed to 720p. The box may be able to give the viewer the option of outputting 720p as 1080i, but again -like everything else with Sky HD at this moment- nothing is certain.