Unknown: how to display cases or matrices?

[peoplemerge]

I don't have a solution for this, but it's my main gripe on equations.

I want to express for example a Master Method recurrence

                     O(n^d log n)   if a=b^d
T(n) = {             O(n^d)          if a<b^d
                     O(n^log_b a)  if a>b^d

In Latex, this works with \begin{cases}. It's probably unsupported now, but maybe that'll change. I'm interviewing next week with Google (wish me luck) so if they hire me I'll be a force for good :) wish me luck.