  We study the spectral and morphological characteristics of the diffuse
Galactic emission in the WMAP temperature data using a template-based
multi-linear regression, and obtain the following results. 1. We confirm
previous observations of a bump in the dust-correlated spectrum, consistent
with the Draine & Lazarian spinning dust model. 2. We also confirm the "haze"
signal in the inner Galaxy, and argue that it does not follow a free-free
spectrum as first thought, but instead is synchrotron emission from a hard
electron cosmic-ray population. 3. In a departure from previous work, we allow
the spectrum of Halpha-correlated emission (which is used to trace the
free-free component) to float in the fit, and find that it does not follow the
expected free-free spectrum. Instead there is a bump near 50 GHz, modifying the
spectrum at the 20% level, which we speculate is caused by spinning dust in the
warm ionized medium. 4. The derived cross-correlation spectra are not sensitive
to the map zero points, but are sensitive to the choice of CMB estimator. In
cases where the CMB estimator is derived by minimizing variance of a linear
combination of the WMAP bands, we show that a bias proportional to the
cross-correlation of each template and the true CMB is always present. This
bias can be larger than any of the foreground signals in some bands. 5. Lastly,
we consider the frequency coverage and sensitivity of the Planck mission, and
suggest linear combination coefficients for the CMB template that will reduce
both the statistical and systematic uncertainty in the synchrotron and haze
spectra by more than an order of magnitude.
