Xcode 5 now supports an -archivePath
option:
xcodebuild -scheme myscheme archive -archivePath /path/to/AppName.xcarchive
You can also now export a signed IPA from the archive you just built:
xcodebuild -exportArchive -exportFormat IPA -exportProvisioningProfile my_profile_name -archivePath /path/to/AppName.xcarchive -exportPath /path/to/AppName.ipa