Looks like Gmail recently made some changes to their interface, and it’s stripping out table cellpadding and cellspacing in HTML emails. Ouch.
There’s a teeny-tiny link at the top of gmail that lets users switch between "old version" and "new version". In the "old version" things work and look fine:
It appears as though using inline-css to define your cellpadding helps. Note that some people in the intertubes are complaining that some inline-css is breaking in gmail too (like line-height).
Since Google is technically a "beta" product, and since it’s free, and since they only just recently made these changes, we can’t complain too much or react too soon.
I have faith in almighty Google. They will fix this. If they don’t do it soon, I have even more faith in "The Chad" (our new programmer). He will modify our templates if we have to. But give it a little time. This kinda stuff happens all the time. Even Lotus Notes fixed most of their HTML email issues (eventually).