Currently, the member titles or levels are from Level 1 to Level 4. Some users get special titles, such as top contributors and/or certified professionals, or even Googler's get a special label, labeling them as Googlers. I do not believe the labels will be changing, but the levels will.
Instead of the 4 levels, there will be 20 levels. Your level will increase based on"
- Posting an answer
- Having your answer selected as the "best answer"
- Having your post rated as helpful
- Rating a post (either as helpful or not)
- Correctly marking a question or answer as spam.
I believe the levels determine what rights you have in the forums. By rights, I mean, can the profile show an avatar? Can they have clickable links? Stuff like that. Each forum sets the rights per level themselves and how hard it is to reach a level as well. So while the Google News forum might be easier to get to a higher level, it might take longer to post a clickable link.
The levels are by forum, so if you have a Level 15 in the Google Webmaster forum, it doesn't mean you have the same level in the Google AdWords forum.