So far I've seen Planet Earth (or some of it, anyway), Blade Runner, and The Usual Suspects on Blu-ray.
Planet Earth is the one that really blew me away - it looks like you could reach into the TV and grab blades of grass etc.
Blade Runner looks fantastic, almost as if it was a really recent movie (other than the somewhat dated visualization of what 2019 will look like), but I'd never seen it on any previous format, so I don't have much of a basis for comparison.
The Usual Suspects is such a kickass movie that you almost don't notice the better picture, but that's probably also because there's not so much complicated visual stuff in it. I don't regret having bought it, but I'm not sure I'd recommend paying the extra to get it on Blu-ray. Especially since there are no special features at all on the disc, which feels like a bit of a gyp.
I also have Across The Universe (that Beatles thing) that we haven't watched yet. That's supposed to showcase the HD stuff really well.
And it goes without saying that PS3 games are fucking beautiful.
We have Planet Earth on Blu-ray. I think Rob and I sat there slack jawed most of the time. I have seen several movies on Blu-ray most of them are just so damned crispy. Others you can't tell much difference. I did notice a HUGE difference in Ice Age 2 on there though. The animation was like "DAYUM!"
I'm no huge fan myself, but some of their more out there shit was OK. I heard the movie is visually pretty awesome though, so I figure it should be fun to watch in any case.
Plus Amy's interested in seeing it, and that goes a long way with me.
My parents bought a PS3 for themselves over christmas. I bought them Planet Earth shortly after that, and they loved it.
Also, quick geekery: the reason some movies don't look any better is because they're not - they're just the DVD stock, upscaled to the right size for 1080p.