(http://www.attenda.net/) and XCalibre (http://www.xcalibre.co.uk/), ie,
large-scale virtualised web hosting? Would you recommend any of these?
Note: I've used smaller virtualised solutions such as Bytemark in the
past for personal projects, but those are too small for this project,
which is to host a number of major websites and so requires the
virtualised equivalent of a small server farm.