  We describe new, deep MIPS photometry and new high signal-to-noise optical
spectroscopy of the 2.5 Myr-old IC 348 Nebula. To probe the properties of the
IC 348 disk population, we combine these data with previous optical/infrared
photometry and spectroscopy to identify stars with gas accretion, to examine
their mid-IR colors,and to model their spectral energy distributions. IC 348
contains many sources in different evolutionary states, including protostars
and stars surrounded by primordial disks, two kinds of transitional disks, and
debris disks. Most disks surrounding eary/intermediate spectral-type stars (>
1.4 Msun at 2.5 Myr) are debris disks; most disks surrounding solar and
subsolar-mass stars are primordial disks. At the 1--2 sigma level, more massive
stars also have a smaller frequency of gas accretion and smaller mid-IR
luminosities than lower-mass stars. These trends are suggestive of a stellar
mass-dependent evolution of disks, where most disks around
high/intermediate-mass stars shed their primordial disks on rapid, 2.5 Myr
timescales. The frequency of MIPS-detected transitional disks is ~ 15--35% for
stars plausibly more massive than 0.5 Msun. The relative frequency of
transitional disks in IC 348 compared to that for 1 Myr-old Taurus and 5
Myr-old NGC 2362 is consistent with a transition timescale that is a
significant fraction of the total primordial disk lifetime.
