It really depends upon how fit and energetic you are and how much time you'll have--you COULD walk from Chez Panisse to the Greek Theatre at UCB, but I imagine not many people would choose to do so. It's a good 7+ blocks from the restaurant's location on Shattuck, south to University Ave. and then it's a steep walk up (east on) University, maybe a bit less than a mile to get to the Greek. You can also take Hearst east to Gayley south. You may want to contact Chez Panisse (www.chezpanisse.com) or otherwise check on bus stop loc's close to the restaurant so that you could get closer to the Greek.

ForestVillian puts it well and accurately. However, if you're moderately fit and have the time, you should be OK. It is definitely uphill.