Added April 23:
Q: Are we allowed to use own own textures or textures we built or are building?
A: You're welcome to use whatever textures you want, provided they are legal to use and don't infringe on copyrights

Q: Can I start planning my map out on paper before the competition starts?
A: Yes, you can start planning it out at anytime. However, you cannot start mapping in Radiant until the competition officially starts in early June. Announcing the competition early allows people to think about potential designs and/or themes.

Added April 26:
Q: Are we allowed to test the map with players during build process (online or lan), for balancing purposes?
A: Definitely, and I strongly encourage that. Anything you can do to ensure that your map is balanced, solid, and perfect is a good idea. The judges will be judging the map on pretty much everything, from playability to overall looks.

Q: I'm in. Where do I register?
A: Make a post in the mapping forum with the title: <map name> by <your name>. Include this information:
-Your name, or handle (ie: John "Pwner" Smith or Pwner)
-Your email address (if you prefer not to write it then PM me it)
-The type of map you intend on making (CTF, TDM, FFA, etc) and the number of players it will hold (this is tentative information and is used by me to pick judges)
-Your website, if you have one, so I can link to it and give you some hits

Added April 27:
Q: Will there be test servers available where people can try out maps prior to the competition ending?
A: Yes. As maps enter the alpha/beta stage and are ready for testing servers will be put up in the US and Europe. There is a post about it here

Added May 2:
Q: Are maps allowed to be released as beta's then re-done later on?
A: The map created must be a completely new map that was created specifically for this competition. This means the map is created when the competition starts and not beforehand. You are welcome to continue working on the map after the competition ends and I will gladly update the competition's mappack with your map's changes as long as the map still has sponsor logos in it.

Q: Are we allowed to make the logo's decals instead of billboards?
A: All of the sponsor logos must be integrated into the maps untouched (image proportions must stay the same, no retouching, no recoloring, etc.). They don't have to be on billboards, but they must be plainly visible to all players on a vertical surface like a wall. In previous competitions mappers have chosen to display them straight on the walls, while others have chosen to integrate them into the environment or on billboards. Each sponsor logo must be on its own display area; image rotations aren't acceptable.

Added May 3:
Q: There are some rules from the previous competition which I don't see mentioned on the current rule list. Have the rules changed? Someone told me about a rule but I don't see it listed on the official rules.
A: Yes. Several rules have changed significantly, so be sure to (re)read the rules on the main competition site. If something is still unclear please post about it.

Added May 4:
Q: Are teams allowed, or what is meant by the term "teams" in the rules?
A: Mapping teams (of more than one person) are allowed to participate, but only one map per person is allowed to be entered into the competition. You can't be on a team and submit a map in addition to submitting your own individual map.

Added May 25:
Q: Are we going on the honour system for [when we start]?
A: Please see this thread about posting your progress and how to prove you are starting at the right time.

Q: The competition has started, when will we get the logos for the sponsors?
A: I'm waiting for the final images to arrive from the sponsors. I will make a forum post with all the images as soon as possible.

Added June 8:
Q: I've started on my map and posted my screenshot with the secret word. A new secret word has been posted but I have no new progress to show. Do I have to post a screenshot?
A: Yes, once you start your map and show progress you must continue to post screenshots, at least one per week, with that week's secret word in it.

Are we going on the honour system for this?

As the competition start gets closer I'll announce a few additions to this rule to "encourage compliance"

Wow, I can see that more and more ppl want to participate in the competition. Congratulations and thank you Maverick for this. It's really great that somebody wants to do something like that.

You're welcome ShadoW, but I can't help but notice that you haven't entered yet. *cough cough*

I'm not sure I'll enter the competition at all . Right now I'm really overworked, so I don't have time to this, but I would really like to participate. I will decide about this near competition start time .

Man I'd love to get in on this. Hopefully all of my job hunting and misc moving stuff is out of the way in time!

Really excited to relearn Radiant!

When's the deadline for this competition anyways? I'm seeing people with a ton of work already done and a lot of people seem to have enough done to release an alpha. I'm still futzing around with layout

The end date is actually written on the official mapping.maverickservers.com page. August 3rd. You've got plenty of time.

Is there an archive with sponsors images anywhere? Or I missed it somehow .

Sorry, I'll be posting those tomorrow. AMD still has yet to get back to me with very high resolution images, but I think I've got everything else. I'll be making a new thread about those.

To follow up with the sponsor logos:
http://maverickservers.com/forums/viewtopic.php?f=10&t=16843

Note: I have yet to receive the sponsor logos from ATI/AMD. I'll post them as soon as they come in.