what is the latest supercomputer and which company manufactured it?

Answer 1

Your timing is impeccable! Just announced today: http://www.engadget.com/2006/07/31/japanese-supercomputer-breaks-the-petaflop-barrier/

Answer 2

It's hard to say "latest", because new ones keep getting built all the time. Most of the top systems these days are built by IBM. I acutually helped build a system that was #3 in the world at the time - it's slid down to #28 in only a few years.

A list updated every 6 months of the top publicly announced systems is at http://www.top500.org - note that it does *not* list some classified systems whose existence is a secret.