Welcome to our first day of covering the season’s two big startup conferences — DEMOfall 08 and TechCrunch50. Here’s a little primer on the two conferences, and how VentureBeat is covering them.

DEMOfall, of course, is the fall arm of the DEMO conference, a well-established launching pad for many startups — 72 this time around, and located in San Diego. TechCrunch50, on the other hand, is the second, expanded iteration of tech news juggernaut TechCrunch‘s conference, which is was called TechCrunch40 last year; as implied by the name, the conference added 10 startups this time around. It will unfold in San Francisco.

And, yes, they’re taking place at the same time. DEMO started yesterday and ends tomorrow, while TechCrunch50 starts today and ends on Wednesday. TechCrunch founder Michael Arrington says the scheduling conflict was unavoidable on his end, because that’s when his desired venue, the San Francisco Design Center, was available. Arrington, however, has also been clear in his intention to take on DEMO and its pay-to-play model: Startups pay tens of thousands of dollars to present at DEMO — and many believe they got their money’s worth — while the selected companies present for free at TechCrunch. He’s even declared “DEMO needs to die.” (DEMO has taken out advertising on VentureBeat and my editor Matt Marshall will be moderating a venture capital panel there tomorrow, but we’re not taking sides. We’ve got just as many people covering TechCrunch, and we’ve partnered with them before and hope to again.)

The conferences have taken very different approaches to media coverage. Whereas DEMO released a list of companies on Friday and allowed the news media to publish articles on all companies this morning (hence the flood), TechCrunch50 has taken a much more controlled approach. The list of the day’s presenting companies is published each morning, and little advanced information gets released, so announcements have to be covered live. I guess that makes it more exciting, but it also creates problems when the conference venue has serious Internet problems. MG Siegler tells me that Arrington just asked the audience if the Internet was working yet and was met with boos.

Another interesting difference is the fact that startups presenting at TechCrunch50 can check a box to have their applications sent to event sponsors like Sequoia Capital, and in fact held their rehearsals at Sequoia’s offices. (When asked about this, event organizers insisted that Sequoia doesn’t have a “first-look” option at these companies, pointing out that this is more of an opt-in that the company chooses than any sort of exclusive look.)

As for VentureBeat, we’re covering the heck out of both events. You’ve already seen Dean Takahashi’s many DEMO posts this morning, with more to come. Apparently videos of company demos will start going up tonight, and we’ll add them to old posts when it happens. And you can follow “tweets” from DEMO attendees on micro-messaging service Twitter here. We’ve also got a FriendFeed room where MG is liveblogging TechCrunch50. Actual posts are sparser for now, due to the aforementioned Internet problems. (I’ve embedded a video stream from TechCrunch50, below, but I’ve stuck it behind the jump because it starts playing automatically — click on the “read more” link to see it.)

You can see all of our coverage in on our special DEMO/TechCrunch50 page, which will also include some unique content, like more liveblogging posts. It’s going to be a crazy few days.