Even though your rendering removes horizontal scrolling, are you looking at ways to better utilize trackballs in some mobiles? BB Pearl, Sidekick, several others take a step to move beyond the D-Pad in most mobile phones, it would be nice if Opera can keep up with them. (Eddie_Lopez)
The BlackBerry Pearl trackball has wonderful speed and precision. We think we can make even better use of it in the future.
What is the makeup of the development team? How many "core" developers do you have and how many other teams contribute.. ie- how large is the project? (Eddie_Lopez)
The main roles in the "core mini" engineering team are: client developers, client quality assurance (supporting 600+ devices is a lot of work!), server developers, server quality assurance, system administrators, delivery managers and project managers.
In addition to these we use a lot of resources provided by other teams in Opera. The translation team helps us translate Opera Mini into 35+ languages. We use the same Opera Core as e.g. the desktop Opera, but on the serverside.
Will there ever be support for a 90-degrees rotated mode? (tinhoy)
The main reason that we have not done this so far is that it currently is not possible to rotate the dialogs and prompts provided by the phone's UI. Thanks to the SSR rendering there is also relatively little benefit in making the screen 20% wider, compared to when using regular rendering.
We are however keeping our options open on this issue.

Generally speaking...are vendors coming to you guys? Or are you shopping Mini out to all the vendors? (Eddie_Lopez)
It's a combination. Opera Software of course has many well-established lines of communications with manufacturers and operators, having been in the mobile browsing business for quite some time now. There are also many cases of companies coming to us. Meeting a new operator/manufacturer for the first time only to realize that the people there are hardcore Opera Mini fans happens fairly regularly, and it does give your a warm fuzzy feeling.

Keep the questions coming!
Finally, here's an action shot of one of the main developers (Mr White) celebrating the birthday in front of the Opera Software office in Linköping, Sweden: