yes, best practices is to have 5 replication partner.
Best practice is to keep the number of replicated sites below 5, and it is strongly recommended to not go over 10 replicated sites.
check this article
http://www.symantec.com/docs/TECH92051

Yes you cango for. Agreed with above comment

additional information
You should keep the number of replicated sites under five
http://www.symantec.com/docs/HOWTO81147

My SEPM is running on XEN 5.0 enviorenment. I want to create a replication server on ESXi 2.0 vmware ennironment. My SEP version is 11.x. also I want to migrate SEP version from 11.x to 12.x ? Hostname and IP will be different.

Which way I should follow:

1. At first migrating SEP version to 12.x then creating a replication server VM wareEnvironment.

or.

2. Creating a replication server on VM wareEnvironment then migratinng ? 

I'd recommend upgrading first, as there have been load of fixes to replication applied since the RU6 days (plus it also means you can keep your new SEPM a little cleaner by leaving out IIS ).

you can go either way whichever is feasible.
However as a ease upgarde the existing SEPM to 12 version. Becuase if you use the replication with SEP 11 RU 6, you need to upgrade the other server to SEP 12, which would be bit time consuming. Hence upgrade to SEPM 12 and other server install SEPM 12 and add as a replication partner.

I've to know two more things:

                            1. Does SEP 11.0.6.. supports replication on different OS platform ?

                             2. Does SEP 12.x supports replication on different OS platform ?

Hello,

Please let me know your problem is resolved or not.

So SEP 12.1.2 is not supported /or may not work properly on VMware ESXi 5.0 or VMware ESXi 5.1 ?

check teh VMs supported, check the implementation guide.

VMware WS 5.0 (workstation) or later
■ VMware GSX 3.2 (enterprise) or later
■ VMware ESX 2.5 (workstation) or later
■ VMware VMotion
■ Microsoft Virtual Server 2005
■ Windows Server 2008 Hyper-V
■ Windows 8 Server Hyper-V
■ Novell Xen
■ Virtual Box, supplied by Oracle

Ok I wanted to know also this two things: Say I've SEPM installed on windows server 2003 and I want to install it's replication partner on windows server 2008 or else.So the questions are:

1.Does SEP 11.0.6.. supports replication on different OS platform ?
yes, only care is SEPM have to be on same version.

2. Does SEP 12.x supports replication on different OS platform ?
yes, only care is SEPM have to be on same version.

How to install SEP replication partner on SEP 12.x ? And some documents related to SEP 12.x replication.

How to add "Replication Partners" and Schedule Replication

http://www.symantec.com/business/support/index?pag...

About installing and configuring Symantec Endpoint Protection Manager for replication

http://www.symantec.com/docs/HOWTO26797

Installing Symantec Endpoint Protection Manager for replication

http://www.symantec.com/docs/HOWTO26796

Best Practice for setting replication frequency

http://www.symantec.com/docs/TECH91509

Best practices for replication server sizing

http://www.symantec.com/docs/HOWTO53365

Check this video

https://www-secure.symantec.com/connect/videos/rep...

Check this article.

https://www-secure.symantec.com/connect/articles/r...

Thanks a lot all the guys (specially to pete). I,ve another quaries:

Level 1:

 Say I've  a SEPM (no.1 server) with a replication partner (no.2 server) running 11.x version. I migrated to new version 12.x.

Level: 2

Then I've created another replication partner(no.3 server). Now I want to remove my main SEP server(no.1 server) and use the new replicated partner(no.3) as main SEP server and as it's replicated partner I want to use no.2 server.

My questions are:

1. On level 1 if I migrate SEPM from 11.x to 12.x, will the replicated partner(no.2 server) automatically migrated to the new version or I've to also migrate that manully ?

2. On level 2 which procedure should I follow to perform ? Is there any risk of losing clients communication with SEPM(no.3 server) ?

1. On level 1 if I migrate SEPM from 11.x to 12.x, will the replicated partner(no.2 server) automatically migrated to the new version or I've to also migrate that manully ?
upgrading SEPM has to be done manually

2. On level 2 which procedure should I follow to perform ? Is there any risk of losing clients communication with SEPM(no.3 server) ?
move the clients to the required server ( no2. in this case) using management server list. once all the clients are reported to the srever , you can decomission the main server i.e. SEPM 1.

Dear Pete, on level 2 I need more clear concept. It will be helpful if U can provide me some related documents to do this.

Dear Pete I am asking too many question to U. I'm appolizing for that. Which port number should I use,when I'm configuring a new management server list. 8014 as previous or 80 or else?

the port on which SEPM listens, default is port 8014.

Thanks a lot.....................................Pete.