Moving tfrom Shimano 9- to Shimano 10- speed I'm thinking of changing the 9-speed Tiagra rear mech on one of my (road) bikes to something, still Shimano, but 10-speed.

The obvious replacements I'll need are cassette, right-shifter and chain. But I reckon because of the narrower chain I'm also looking at a new chainset and rear derailleur. However I think the front derailleur and left-shifter should be safe (still keeping the front mech the same). Ditto the bb, regardless of whether I need a new chainset

Has anyone actually done this conversion and is able to confirm (or put me right)? 
Thanks

Update

Decided in the end that going from 9- to 10- was too much to spend all in one go. But I used a service as an excuse to change the cassette (to a 9-speed ultegra) and the chain (dura ace) at quite minimal cost. Can upgrade other parts as and when, although I'm basically looking at Shim's 6500 range here so all quite dated now.
You will need a 10-speed cassette, 10-speed rear derailleur, and 10-speed right side shifter and a 10-speed chain to work with the narrower spacing on the rear cassette. There tend to be some compatibility issues with 9-speed derailleurs run on a 10-speed drivetrain (some people seem to have luck using 9-speed shimano mountain derailleurs with 10-speed shifters, but YMMV).  

Your 9-speed front chainrings should be fine.  Sheldon seems to agree on that point However, I wouldn't expect it to work on 8 or 7 speed chainrings, but it very well may.  I've upgraded my own 10-speed outer front chainring with a 9-speed one on a 10-speed Tiagra setup and haven't had any issues with it. There shouldn't be any issue with the left shifter, derailleur, or bottom bracket, those should be fine as well.

One other thing to consider is the brakes. 10-speed STI shifters may have a different lever pull ratio than the 9-speed levers, this may only apply to ultegra and dura ace though (please correct me If I'm wrong on this). So, you'll probably be OK if you're sticking with tiagra.  Otherwise, you may want to upgrade STI levers at the same time and possibly get brakes with a matching pull ratio.