Interesting Wall Street Journal article, Bartering to Avoid Taxes; Popular Real-Estate Strategy Is Increasingly Used to Defer Capital Gains on Other Assets, by Rachel Emma Silverman:

In recent years, 1031 exchanges have soared in popularity, mostly with real estate, as investors have flocked into the real-estate market and prices have skyrocketed, leading to big capital gains that investors have been eager to put off. But as people grow familiar with the tactic, and are diversifying into a wider variety of investment assets, some are now doing trades with other types of property, including art, collectibles, private jets, collector cars, yachts, copyrights, race horses, even Web site addresses.

The total value of all property involved in 1031 exchanges jumped to $175 billion in 2003, the latest figures available, compared with roughly $90 billion in 1999, according to estimates from Deloitte Tax LLP, a unit of Deloitte & Touche USA LLP….

One such trade happened in early November, when bond investor Bill Gross traded a block of four rare 1918 stamps for another very unusual stamp, an 1868 "Z-grill" stamp depicting Benjamin Franklin. Mr. Gross had bought his block of four stamps, which depicted an upside-down biplane, only two weeks before the trade for $2.97 million. The Z-grill, meanwhile was owned by Donald Sundman, president of Mystic Stamp Co., Camden, N.Y., who had purchased the stamp in 1998 for $935,000 as an investment; the stamp’s value had now climbed to nearly $3 million with the trade. The swap was structured to comply with the 1031 rules, say individuals familiar with the transaction.