ESN Manufacturer Table
This table lists ESN manufacturer codes and serial number ranges. All entries are in the decimal format, which is explained on the CDMA Hardware IDs page.
To determine the manufacturer given an MEID, first convert it into the decimal format. This is a 3-digit block and an 8-digit block. Look up the 3-digit block in the "Manufacturer Code" column, then determine which range the serial number falls into by looking at the First/Last Serial Number columns.
This list was last updated in March, 2009. I don't anticipate updating it again.