I gave out some misleading information associated with the continuous improvements made to the 2008 Madone's seat cap design.  I want to set the record straight.

Visually, the difference is that the newer cap has a painted clamp and the carbon portion of the cap is now 10mm longer.  The added length allows for a broader range of height adjustment.  The added length applies to both the standard and long caps and to all three seat offset options.

The new black clamp is also positioned at 90 degrees to the cap (not angled like the original) so the clamp is more effective.  This 90 degree repositioning decreased the torque required to keep the cap in place.  The clamp bolts are now torqued to 5-7 N*m.

The section width of the revised clamp is 15mm narrower on the new clamp so rider's legs have even more room.

These revisions went into place in September of 2007 and were on sale to consumers in October of 2007. 

The internal dimensions of the older and newer cap are the same.  The caps are interchangeable, the clamps are not.  Trek dealers are not exchanging old for new but new caps can be purchased individually.

Hope this info answers any questions you have.

Above is the new clamp design.  Below is the old.