Multisite scalability / Multi-DB

Hey all,

i wonder if there's anything around about scaling a multisite/blog hosting solution? I currently do only host around 100 blogs until now but the database is growing enough so as i have to move servers soon i was thinking about which way to go.

I've been a bit surprised seing the Multi-DB plugin not beeing developed anymore - AFAIR it was widely used back in the days - are there other solutions that i didn't see so far? How do you guys with bigger blog hosting services do this now?

Thanks for any input.
Frank