Formerly in Creo 3, a HTTP path could actually be used to reference models in Creo. This was used for a time to pull for example, a curve .ibl file from a version control system like Subversion, into an import feature. The HTTP path was convenient because it provided a clear lineage instead of directing to a user's local path.
This functionality does not seem to work anymore in Creo 5, and PTC confirms that this was never within spec. This would be good to put back in the spec for the above reasons.