O2 have announced on their website that the next HTC device they sell will not include a charger in the box, just a microUSB to USB cable, to avoid adding to the '100m chargers' already in the UK.
...we’re working with HTC to try something new – taking chargers out of the box. We’re doing this because our research shows the UK has more than 100m chargers lying in drawers, tangled in cupboards and generally gathering dust. The majority of phones are now upgrades and chargers that use USB cables are now widely used, meaning the bit of plastic that plugs into the wall can actually be used by pretty much every phone.
O2 is encouraging other manufacturers / operators to do the same and on the whole, I think it's a pretty sound idea... so long as it's not used as a way to screw a bit more money out of customers by overcharging for the USB to mains adaptor.
I'm watching you O2, don't undo the potentially good work... ;)