I download XCode 4.1 for Lion and 4.3.2 for Lion from https://developer.apple.com/downloads
After install I had two folders /Platforms with iPhoneSimulator5.0.sdk and /Developer/Platforms with iPhoneOS.platform and iPhoneSimulator.platform.
XCode 4.1 or Dashcode is starting iOS Simulator Version 4.3 (238.2)
XCode 4.3.2 start iOS Simulator Version 5.1 (272.21)
The package XCode 4.1 has Dashcode version 3.0.2 (336).
Dashcode of "More Developer Tools" with XCode 4.3.2 has version 3.0.4 (341)
The first runs the old IOS Simulator.
The second says that there is no SDK.
On the same machine. Seems that something is wrong with Dashcode from "More Developer Tools".
I tried to report this error on bugreport.apple.com but...
"An error has occurred. Please report the error to Apple Inc. by emailing the error detail to devbugs@apple.com."
Well, I sent an email. And waiting for fix.