eBay announced it is expanding its Safeguarding Member IDs (SMI) program to all auction-style listings on eBay.com and Motors. eBay rolled out SMI last year for auctions that received bids of $200 or greater. The initiative was to combat fraudsters who were using fake "Second Chance Offers" to defraud bidders.

SMI works by masking bidder IDs so scammers can't tell who is bidding on a listing. eBay said in its announcement:

For over a year, these masked User IDs have proven to be very successful on these higher-end listings. In fact, we saw the volume of fake Second Chance Offers for $200 or more drop significantly. We've also worked to educate members about the importance of unique email addresses, and we have aggressively targeted members who have risky User ID/email combinations to encourage them to change. Please note - If your User ID matches your email address, please protect yourself by changing your User ID so your user ID doesn't match your email address.

SMI is controversial among buyers who wish to see who they are bidding against and also try and spot evidence of shill bidding. You can read more, including commentary from eBay, and leave a comment on the AuctionBytes blog:
http://blog.auctionbytes.com/cgi-bin/blog/blog.pl?/pl/2008/3/1204572683.html