Seems portable from what i can see. To what extent, i still don't know, but IMO still worth to mention it here to see what you think.HostsXpert is an ultra-groovy Hosts file Manager, Editor and Helper-outter.
I read about it while downloading the latest host file from mvps.org and they mention the portability of it also.
== off tipic ==
This is my first post also. Been lurking and using the site for some time and finally signed up.