Should Capital Gains be Taxed at a Lower Rate?

Since 1921 when a special rule was provided for capital gains, how such income should be taxed has been a topic of regular debate in Congress and among others. The Congressional Budget Office's Budget Options, Vol 2, released in August 2009 includes as a revenue option, maintaining the current 0% and 15% rate structure for capital gains. [See page 180-181 of the CBO Report.]

One argument is to alleviate the double taxation of corporate income. Counterarguments include that a lower tax rate for capital gains favors higher income individuals who have more of this type of income than do average taxpayers.

What do you think? How should this debate over how to tax capital gains be structured - what are the important points? Are there alternatives? If taxed as regular income, what should we do with capital losses - should they be usable against any type of income?