Miller cracked Safari running on a fully patched installation of Mac OS X on a MacBook. The details of the exploit will not be given out until Apple has published a patch to ensure that others don't run with the exploit and abuse it. This is the second year in a row that Safari on the Mac is the first to fall in the PWN2OWN contest, again by Miller's hands.
A while after, Internet Explorer 8, running on Windows 7, also fell. Windows 7 was running on a Sony Vaio P, and was cracked by a cracker named Nils, who wishes to remain anonymous. He also won a cash prize and got to keep the Vaio P. Several Microsoft security folk were on sight to witness the exploit. This exploit is also kept under wraps until Microsoft releases a patch. Later on, Nils also broke into Safari (Mac) and Firefox.
All the cracks happened on day one of the contest, which means the operating systems and browsers were fully patched, with no additional plugins loaded. So far, only Chrome hasn't been cracked yet, but that probably won't take long, seeing how quick the first browsers were exploited.
The phones do not appear to have been cracked yet, so that contest is still underway.