Yes, the flying white things there are the Ghasts. They shoot fireballs at you, and according to Notch, 'When there are this many Ghasts, you don't survive for long'. Specially considering that that red-ish block there burns forever. Yup. Lots of Ghasts throwing fireballs on you and rock that burns forever. That makes sense. It'll be great to be trapped by lots of flying, crying creatures in a hell-ish dimension full of lava waterfalls. Yes, seriously, it'll be amazing.
You see that obsidian doorway there? That's a portal. To make one, make a frame out of obsidian, and set fire to the space inside it. Walk in, you're in Hell (Notch might rename it; a wise decision, since some people might think it's somehow related to religion and that wouldn't be good for his bussiness). If you want to get back to the normal world, you'll have to make another portal - and there's the catch. Place the portal just a bit away from the entrance one, and bam, you're really far. In PCGamer's Tom Francis' words, 'Make one 10 meters away, and you’ll find yourself 160 meters ahead in the real world when you get back'.
He also tells us that there will be six new blocks - five will have new functions. Also coming with the Halloween update are the biomes, one of the features fans have requested the most. Deserts, forests, snowy mountains. Looks like Minecraft's already gorgeous landscapes will be even better.
That update reminds us of Valve's frequent, content-rich, free updates to Team Fortress 2. Notch's been doing quite a few updates (not so many lately, but he has his reasons - he's starting a company) to Minecraft, adding content and even fixing bugs once. One might say it's just because the game is still in Alpha, but the developer has a great connectivity to the community, frequently adding features requested by them. If he will keep this successful bussiness model or, well, change it, only time will tell. For now, let's wait a few days for the next update.
Minecraft's Halloween Update is coming in Sweden's October 31 exclusively for PC. See the PCGamer preview: PCGamer
Update: Ghasts have a small chance of coming through open gates! Yes! http://twitter.com/#!/notch/status/28442542287