Greybar
No Trouble at All
Final answer, from the 3.5 FAQ posted 9/21/2006 (latest) - this is specifically covered:
Is sunder a special standard action or is it a melee
attack variant? It has its own entry on the actions table, but
the text describing it refers to it as a melee attack. Is sunder
a melee attack only in the sense of hitting something with a
melee weapon, or is sunder a true melee attack?
Sunder is a special kind of melee attack. If it were a special
standard action, its description would say so (as the descriptive
text for the Manyshot feat says).
If you make a full attack, and you have multiple attacks
from a high base attack bonus, you can sunder more than once,
or attack and sunder, or some other combination of attacking
and sundering.
Sunder does indeed get its own entry in Table 8-2: Actions
in Combat in the Player’s Handbook. It needs one because
unlike a regular melee attack, sunder provokes an attack of
opportunity (although not if you have the Improved Sunder
feat).
You can also disarm, grapple, or trip as a melee attack (or
attack of opportunity).