I may have installed the devel 32 bit , but I DID uninstall it, and only had x64. Strange.
I uninstalled all the rpms again (rpm -e postgresql90-devel --allmatches) and re-yummed and now slony compiled successfully.
Incidentally I tried removing the -lgport and recompiling and that worked too (After commenting out a few lines) , but I thought that would not be safe.
I am now testing slony with 8.1 to 9.0 and it appears to be going smoothly so far.
Sahol dostum!

Kind Regards
--
Ejber Ozkan

-----Original Message-----
From: Devrim GÜNDÜZ [mailto:devrim at gunduz.org] 
Sent: 24 January 2011 20:27
To: Ejber Ozkan
Cc: slony1-general at lists.slony.info
Subject: Re: [Slony1-general] /usr/bin/ld: skipping incompatible /usr/pgsql-9.0/lib//libpgport.a when searching for -lpgport

On Mon, 2011-01-24 at 09:20 -0600, Ejber Ozkan wrote:
> 
> slony1-1.2.22 compiled ok on 8.1 (FC10) but on CentOS 5.5 with 
> Postgresql90 installed ( I only have to x64 installed of 9.0 from the 
> pgrpms).
> I get a compile error:
> 
> gcc -g -O2 -Wall -Wmissing-prototypes -Wmissing-declarations -I../..
> -DPGSHARE="\"/usr/pgsql-9.0/bin//../share/\"" -DPG_VERSION_MAJOR=9 
> slonik.o dbutil.o parser.o  ../parsestatements/scanner.o 
> -L/usr/pgsql-9.0/lib/ -L/usr/pgsql-9.0/lib/ -lpq 
> -Wl,-rpath,/usr/pgsql-9.0/lib/ -lpgport  -o slonik
> /usr/bin/ld: skipping incompatible /usr/pgsql-9.0/lib//libpgport.a 
> when searching for -lpgport
> /usr/bin/ld: skipping incompatible /usr/pgsql-9.0/lib//libpgport.a 
> when searching for -lpgport
> /usr/bin/ld: cannot find -lpgport
> collect2: ld returned 1 exit status
> make[2]: *** [slonik] Error 1

http://blog.2ndquadrant.com/en/2011/01/how-not-to-build-postgresql-90.html

Could this be the issue?
--
Devrim GÜNDÜZ
PostgreSQL Danışmanı/Consultant, Red Hat Certified Engineer PostgreSQL RPM Repository: http://yum.pgrpms.org
Community: devrim~PostgreSQL.org, devrim.gunduz~linux.org.tr http://www.gunduz.org  Twitter: http://twitter.com/devrimgunduz