Hello Lee,

> 
> I have my eye on a .com domain which was once registered but 
> appears to have expired now.
> 
> When I try to register it (through several regisrars) it 
> still comes up as taken.
> 
> My question for the list is how long after a .com domain 
> expires is it released for registration by someone else.
> 

The process for .com is actually remarkably complex.

(1) After a name expires, it is auto-renewed by the registry operator
(Verisign)
The Registry WHOIS will show this "auto-renewed" date.
Check the WHOIS at: http://www.verisign.com/nds/naming/

(2) A registrar has a 45 day grace period to delete the name from the
registry after expiry.  If the registrar deletes the name in this
period, the registry will refund the registry fee.

(3) A registrar normally displays the original expiry date on its WHOIS,
until the registrant pays for the renewal, the name is transferred to
another registrar, or the registrar sends a command to the registry to
delete the name.

(4) A registrar will often remove the name from the zonefile (a status
called registrar-hold) at some time after expiry to encourage the
registrant to pay for the renewal.

(5) If a registrar sends a command to the registry to delete the name,
the registry will place the name into a 30 day "Redemption Grace Period"
status.  During this period the name can be "redeemed" by the registrant
through the original registrar for a fee.

(6) At the conclusion of the redemption grace period, the registry
operator publishes a list of names that will be deleted from the
registry in 5 days time.

(7) At the point at which the name becomes available (e.g within
milliseconds), automated processes used by registrars attempt to
re-register the name by sending a massive amount of new registration
requests (called an "add storm") to the registry on behalf of customers.
The chances of getting a popular name then become essentially random.

In summary the process of obtaining a name that becomes available has
become highly specialised - especially if the name has any value.  A
value of a name is often determined by how the name was used in the past
(e.g did it have an active website?), how long the name is, and whether
the name is easy to remember or generic in some way.

You might like to check out companies that specialise in the area of
obtaining domain names for customers.
E.g snapnames (http://www.snapnames.com) or pool (http://www.pool.com)
Often registrars re-sell the services of these companies.

Snapnames has a neat diagram of the process at:
http://www.snapnames.com/deleteprocess.html

Note there is also a US patent application that concerns the techniques
for obtaining deleted names.
US patent application number: 2002/0091827 A1; Date of publication: 11
July 2002; 
Filed: 1 November 2001
(see http://www.uspto.gov/patft/index.html for further info.)

Regards,
Bruce Tonkin