Based on your past experience, will two iPhone SDKs co-exist on a single mac?
For example, one that is in beta and one that is released.
I am planning to just copy an existing SDK to a different folder before installing a new one - would appreciate any prior warnings!
When you install 3.2 beta, the others (e.g. 3.1.2) just stick around and are available as target SDKs.
The best way to do that is to have side by side installation. And it is Apple's recommendation to do so as if you plan to release an application on the AppStore it should be built against the official version of the SDK.
You should install the released version (official one) in a directory say 'developer' and the beta one in a folder called for example 'developerbeta'
that way, you will have both versions of Xcode and all the SDKs.
Hope this helps.
Doing not Working's explanation is correct.
The only place you're going to see the official Apple recommendation is by getting a developers account (the free one will work I believe), signing the NDA and then (1) reading the installer readme or (2) checking out the iPhone 3.2 Apple Dev forum.
The SDKs have always been separate from the developer apps like Xcode. You can always compile any project in any version of Xcode with an earlier SDK. That has always been true. However, Apple will not accept any app built with the 3.2 dev tools, i.e. Xcode, Interface Builder, Instruments etc.
I would suggest running the 3.2 dev tools under a different users to prevent any preference file mixups.
You do not need to worry about doing this for keeping iPhone OS3.2 when installing iOS4 - apple has already included 3.2 in the iOS4 installation. But this is a good tutorial if you want to keep iPhone OS 3.0 or any pre 3.2 version for testing.
http://adeem.me/blog/2010/06/16/how-to-setupinstall-2-iphone-sdks-on-one-mac/