Thompson Masterpiece seat post and a Ti railed saddle will not stop squeaking when I pedal. It is definitely the seat post/saddle interface as I can replicate the effect with the seat post removed from the frame and clamped in a vice. Do I :
A) just keep tightening the allen bolts
B) Remove, clean and refit the saddle (again)
C) Remove, clean, grease the rails and refit the saddle (again)
D) Wrap tom duct tape around the rails and refit the saddle
E) Throw the whole lot out the window and fit an i-beam jobbie
fixed my creaky Bell Air the other day by greasing the saddle rails and the seat post clamp. Miles better... silent bike again.
Kev
C)
Or pray for rain when you ride as that seems to stop my saddle squeaking.
Just give it a light dose of WD40 around the rails.
C. but make sure it's Cu grease for best results.
A. and D. are both daft and dangerous ideas
D doesn't work.
lay off the pies it's not squeaking it's groaning 
what is tom duct tape ?
Bel Air and a Thomson post squeaking? cured mine by going with a I beam. before that it was WD40 every now and again.
being running the same combo for ages without a problem. try putting a little spray of lube/grease into the area where the saddle rails go into the saddle shell.
Aye, its the saddle rails going into the saddle which squeak on mine. lube it up!
Don't just tighten up the rails. I've seen a couple of Thomson failures on the internet (at the top of the post) that have been blamed on overtightening, apparently the max torque value is under 7Nm, which is suprisingly little. For the Masterpiece it's even less.
I find a squirt of GT85 helps mine. I've used copper grease in the past but this led to slippage but I reckon good old carbon assembly paste with its extra grip might help too.
--- Edit ---
Have a look at the first news item here [url= http://www.lhthomson.com/news.asp ]http://www.lhthomson.com/news.asp[/url]. The torque value for the Masterpiece is just 5.1Nm!!