Harvesters Heroes has a map with both Cauldron and Sasserine marked on. However, you will have to register on the site (for free) to be able to download them. You can find the map under Downloads > Greyhawk Atlas > Atlas Part 11 The Master Maps of the Flanaess > The Greyhawk DM's Master Map.
Anyway, Sasserine is located on the southern shore of Jenkela Bay at the Amedio Peninsula, and Cauldron is located south of Sasserine in an outcrop of the Hellfurnaces.
I recently bought the Shackled City adventure path and now wants to run it for my group. I want to play in the Greyhawk setting but cannot find neither Sesserine nor Cauldron on any maps. Anyone know where they are located and maybe in which issues of dragon/dungeon I can find more background material?
You can find some backround information about Sasserine in Dungeon #139 and in the backdrop about Sasserine, that paizo will put online in the next week or so.
You should also check out this site concerning material about Cauldron and lots of other useful stuff for the campaign:
http://therpgenius.com/Default.aspx?alias=therpgenius.com/shackledcity