PlayStation 4 is likely to be announced at the PlayStation Meeting taking place in New York City at 6 PM EST tonight. We probably won't see a release date (November 2013?) or price range for various models ($399-$499?) but we're definitely most likely probably in all likelihood going to see some gameplay.
I do not expect to be blown away by the graphics of next-gen and neither should you.
Take Ubisoft's Watch Dogs, for example. An epic gameplay video came out of E3 2012 and it was only later confirmed that this title would be making its way to next-gen consoles (as well as PlayStation 3 and Xbox 360). You can tell that it looks better than what's currently available on consoles, but when compared to PC, I can't say that I'm totally blown away like the jump from SD to HD, or 16-bit to 32-bit.
I suppose as time goes on, more and more people will become aware of PC gaming and how it relates to console development. I'm definitely not saying PC gaming is better than console gaming because of graphics or whatever. I'm just saying, when viewing the next-gen gameplay that we will probably be seeing tonight, don't expect anything too crazy.
Keep your hopes reasonable. Don't break your own heart and stuff.