The just-released Statistics of Income Bulletin (Fall 2004) includes Domestic Private Foundations and Charitable Trusts, 2001 by Melissa Ludlum (SOI).  Here is the summary:

Nearly 70,800 private foundations filed Forms 990-PF and reported disbursements of nearly $27.4 billion in contributions, gifts, and grants for Tax Year 2001.

For related data, see here.  For other private foundation and charitable trust data, see here.