http://jhbuild.bxlug.be/builds/2006-04-29-0005/logs/gnome-keyring/#build

gnome-keyring does some of casting from guchar* to guint32*, along with some other implicit casting involving GArray which involved a twisty maze of macros. Anyway, the net result is the alignment of structs is more strict on Solaris, so adding -Wno-cast-align at the bottom of configure.in fixes that.

The warnings about formats:
gnome-keyring-daemon-io.c: In function `gnome_keyring_client_state_machine':
gnome-keyring-daemon-io.c:369: warning: unsigned int format, uid_t arg (arg 4)
gnome-keyring-daemon-io.c:369: warning: unsigned int format, uid_t arg (arg 5)
and 
gnome-keyring-daemon.c: In function `main':
gnome-keyring-daemon.c:2779: warning: int format, pid_t arg (arg 2)
gnome-keyring-daemon.c:2801: warning: int format, pid_t arg (arg 2)
gnome-keyring-daemon.c:2808: warning: int format, pid_t arg (arg 2)

I'm not sure how to get rid of these without -Wno-format, as by default on SPARC/Solaris they're #defined as long for 32bit code, which is 4 bytes long. Compiling with -m64 would #define them as int, which would still be 4 bytes long, but the right type for the format string. Possibly cast the uid_t and pid_t to int?

http://www-128.ibm.com/developerworks/library/l-solar/ is a useful reference for this sort of stuff.