Are all of your sites on the same server? If they are you could do what
I have and just place one copy of the whole framework on the server in a
central location that all sites can access. All you need to be careful
of is that if you have five sites running on 1.0.0 and 1.1.0 comes out
you don't overwrite 1.0.0, but upload 1.1.0 in addition to 1.0.0,
otherwise it could break the other sites.
Of course if they're not on the same server then you wont have this
option, but you could use an FTP client with a synchronisation feature
so that you're only uploading the modified files each time, rather than
the whole site.
--
Jack