I need to know all information pertaining to creating poker software (not the
site but the software for an online site). Are there any freelancer's
that you know that are in this business?

I am a software engineer and poker enthusiast.  I originally started
playing on line 2 days after I started researching texas hold em
sites, because I was interested in writing my own poker software.  Of
course, after finding 20 existing sites that offered texas hold em, I
realized that my efforts would be futile in a saturated market without
strong backing/support that an unknown developer would not be able to
get easily.

I would be able to give you a brief explaination of how sites work in
general.  Is that all you are looking for, or do you want something
more specific?

My client has the backing/funds necessary and is only interested in
creating the software and not the site. Any background information on
the subject would be very much appreciated. Thank you

For $15, I'm not willing to give more than a brief overview.  So here goes:

Obviously, you need a server and a client program.  The server program
stores all relevant information about all games, players, the shuffle
algorithm, etc.  It would also need to keep tabs on all players by way
of either a constant connection or a periodic burst packet of info. 
Choosing one method over the other requires much more analysis as to
your given environment.

Connected players would only receive the information they need to know
at the time, meaning, when the cards are dealt, the server only sends
you your hole cards.  Then, when the first player makes his decision,
he would send the decision to the server, who would then relay it to
all players at the table - where their local software would represent
that action.  The next player makes his move, and the same
communication would happen.

When a hand is over, the server would send all information to all
players, who would then see that information represtented on the
screen, with player amounts updated, chips visually moved over the
screen, etc.

The kind of connection necessary for this communication can be
achieved over the internet with a protocol known as TCP/IP.  Many
methods to use this protocol are available, such as the WinSock
Control from Microsoft.

However, aside from the games themselves, there are many support
features you will need to take into account as well, such as game
managment (ability to move players from table A to table B manually or
automatically), money managment (could outsource this easily), player
support (real time), etc.

There are a few companies who host "skins", which means they let you
use their software (and accounting modules) with slight changes to
name of site, color scheme, etc.  It might be more beneficial to look
into leasing existing software, unless of course, you want new
features or to add games these skins don't provide.

That's really good. My client wants to develop his own software, so
leasing is out of the question.

If I post this question back up for 50$, will you give me a more in
depth explanation? About the GUI also, hand history, how long it would
take to develop and how many programmers would it require etc...