ICANN has just launched a forum to discuss the methods for allocating single letter and single digit domain names for all 16 gTLDs (AERO, .ASIA, .BIZ, .CAT, .COM, .COOP, .INFO, .JOBS, .MOBI, .MUSEUM, .NAME, .NET, .ORG, .PRO, .TEL, and .TRAVEL)

a.com b.info 4.biz etc. 

Some of the .com’s are already owned z.com by Nissan x.com by Ebay/ Paypal but these predate 1993 when the current reserved names policy was imposed.

ICANN Announcement
ICANN Discussion Forum