I recently received an ipad app as a .ipa file.
To install the app, i renamed it to .zip and fished out the app file and using the Iphone Configuration Utility was
I checked it myself and figure out that when you create an enterprise IPA - it for all devices, with:
ProvisionsAllDevices
and when it an ad Hoc, it only for limited devices:
ProvisionedDevices
caf2b03e4a4e1a80d9492c8bdcea0ea8df6a14a7
1a5b7515ed0751d6de312f9520267f502b20eab0
f4c368bb6c27119feb877e0d95d3891166ab48c8
72234de7149e980a9e659e5417f764c47c5e7327