Tried this in m.p.framework a couple of days ago with no response.  I'll try here:

I'm loading an assembly from a URL using Assembly.LoadFrom().

Is there any way to tell if the current version of the assembly
already existed in the application download cache.

I need to do an expensive operation each time the assembly changes,
but I'd like to avoid it if the assembly hasn't changed (although
functionally it works if I do it every time I load it).

If there's not an automatic way, I guess I write logic to manually
check the timestamp of the assembly on the server and compare it
against a locally stored timestamp.  I'd rather not have to do that
though.

Thanks for any help!