Description of problem:
There are two problems here, but i think one of them is already fixed by a newer version of m2crypto.  Anyway...
On an i386 provisioned box from beaker, I am getting an error when subscribing to a subscription.

Problem 1: Using the subscription-manager-gui, an error occurs when subscribing.  From the attached screenshot, the error message is not getting populated in the error dialog:
Error getting subscription: %s

The corresponding traceback is:
Traceback (most recent call last):
  File "/usr/lib/python2.4/logging/handlers.py", line 71, in emit
    if self.shouldRollover(record):
  File "/usr/lib/python2.4/logging/handlers.py", line 149, in shouldRollover
    msg = "%s\n" % self.format(record)
  File "/usr/lib/python2.4/logging/__init__.py", line 617, in format
    return fmt.format(record)
  File "/usr/lib/python2.4/logging/__init__.py", line 405, in format
    record.message = record.getMessage()
  File "/usr/lib/python2.4/logging/__init__.py", line 272, in getMessage
    msg = str(self.msg)
TypeError: __str__ returned non-string (type NoneType)


Problem 2: Using the command line tool, you will also see an error when subscribing...

[root@dell-pe2550-01 ~]# subscription-manager list --avail
+-------------------------------------------+
    Available Subscriptions
+-------------------------------------------+


ProductName:       	Red Hat Employee Subscription
ProductId:         	SYS0395                  
PoolId:            	8a85f9812ede00af012edf01c89f5cf9
Quantity:          	9993                     
Expires:           	10/07/2011               

[root@dell-pe2550-01 ~]# subscription-manager subscribe --pool=8a85f9812ede00af012edf01c89f5cf9
Entitlement Certificate(s) update failed due to the following reasons:
	- Serial number must be > 0
	- Serial number must be > 0


Version-Release number of selected component (if applicable):
Verifying Version on i686...
[root@dell-pe2550-01 ~]# rpm -qa | grep subscription-manager
subscription-manager-0.95.5.15-1.el5
subscription-manager-gnome-0.95.5.15-1.el5
subscription-manager-firstboot-0.95.5.15-1.el5

[root@dell-pe2550-01 ~]# subscription-manager facts --list | grep uname
uname.machine: i686
uname.nodename: dell-pe2550-01.rhts.eng.bos.redhat.com
uname.release: 2.6.18-259.el5
uname.sysname: Linux
uname.version: #1 SMP Fri Apr 29 01:10:46 EDT 2011

[root@dell-pe2550-01 ~]# rpm -q m2crypto
m2crypto-0.16-7.el5


I suspect a newer version of m2crypto will fix the subscribe errors.  However, it may avoid the problem of the error string not getting populated in the error message dialog:  
  Error getting subscription: %s

PS. I don't think the i386 arch is a factor in this bugzilla.