i doubt we will get miui... atleast until we get ics.. then maybe someone can get miuiv4 ported...
but if you want the miui feel you could do like im doing...
-milocker - has all the miui lockscreen themes
-exdialer - miui styled dialer/contacts
-go launcher - i placed all my apps on the homescreen and moved the appdrawer from the dock onto a page(in case its needed) and i changed the market settings to auto add shortcuts... i went on xda and downloaded a few icon packs that i like and i change the icons individually..
it takes some time and patience to get it all perfect.. but i like the fact that i can set any icon to any app.. i get too picky with themes because of the few icons that are missing or dont fit my taste..
theres also ilauncher on the market.. it works perfect with the spectrum.. but no widget support