By not publishing the M3 figures the Fed removes their intellectual authority from the calculation. The numbers will still be available from other parties but the Fed can sow confusion as to the reliablity of those 3rd party calculations. I have no idea if that was part of the decision but it fits the Bush administration's operational pattern.
M3: M2 + all other [>$100,000] CDs, deposits of eurodollars and repurchase agreements.
Eurodollars are deposits denominated in United States dollar at banks outside the United States, and thus are not under the jurisdiction of the Federal Reserve. Subsequently, such deposits are regulated much less than similar deposits within the United States, allowing for higher margins.
The more accurate and descriptive term is Sale and Repurchase Agreement, since what transpires is sale of securities now for cash by party A (the cash borrower) to party B (the cash lender), with the promise made by A to B of repurchasing those securities later (with A paying the requisite implicit interest to B at the time of repurchase - the implicit interest rate is known as the repo rate).
The US Federal Reserve and the European Repo Council (a body of the International Securities Market Association) both try to estimate the size of their respective repo markets. At the end of 2004, the US repo market reached USD 5 trillion and the European one passed EUR 5 trillion in outstandings. Both are growing at two-digit pace.