Take a peek at the AD7763 (one channel current/voltage/temperature/frequency) or AD7816 (adds voltage measurement for six channels). You'll find these types of "energy management" chips from many manufacturers, and this is the type of thing I'd assume you'd find in commercial PDUs. These particular chips have an SPI output so you could string up quite a few outlets with them.
With respect to using triacs, I have an APC rackmount unit with 8 switchable outlets; it uses relays for switching. It seems like a latching relay would be the best way to go -- you'd be able to "reboot" the PDU without affecting power output to all of the connected devices.
Regarding switching power, that's not uncommon in a datacenter, Henry. Being able to power cycle a server remotely is a big advantage in corporate environments when the support is "outsourced". I could tell you stories about on-site support breaking power switches on servers when they were asked to power cycle them.