Sounds like a broken record, I know; thankfully, the nice folks at ConfigServer gave us a 20% discount on the tuning they do for us because we just had it done 10 days ago. [I didn’t even ask for it; they just did it. They rock.]
As a result, I expect that the tuning will happen tonight. In conjunction with the changes already made [we’re now running Apache2 and PHP5], they’re going to upgrade MySQL to 5.0 from 4.1. There really shouldn’t be any issues with that, but if you use a database-based application and have problems after the upgrade, let me know and I’ll help you work them out. [WordPress, SMF, and phpBB are all abstracted enough that I really doubt it’ll matter.]
ConfigServer’s based in the UK, so any downtime would be late Monday evening into early Tuesday morning.