Hey Guys, first of all thanks for your great Application because Messenger:mac form Microsoft is something you won't have installed.
But the current SVN-Version has some Bugs and I want you to know about them.
Here are my System-Infos:
Installed OS: 10.6.1 - Build 10B504
Installed aMSN: 0.99b - SVN-Version 11682
Computer: iMac 7,1 with 2,0 Ghz Core2Duo Processor and 4GBs of Ram.
So first the start-up performance of aMSN under Snow Leopard is not very well, it sometimes needs about 2 Minutes till it can be used. (That is not a bug but I want to know it you.)
Then, when I log-in, always my Firewall asks me, if I want to allow aMSN to accept incoming network connections.
Also, aMSN is not compatible with Spaces. The information-windows only appears in the Space, where aMSN is active and the same problem with the System-Icon windows.
aMSN is the only application with these problem and so I think it is not a bug by Apple.
Next, since aMSN 0.98 Beta 4 there is a little issue in the Tabs-Appearance. The Close-Button is not at all at the right Corner.
Let my show it with a little Screenshot:

Then there is one more Bug. It appears sometimes when I want to open the Chat-History of some Contacts. When I click, the AMSN-Error window appears and after sending report or not, an empty Chat-History window appears like this:

But this Bug appears only by some contacts, not by all.
So that are all Bugs I realize during using aMSN daily.
In the end I want to give you an idea for improvement in the OS X Version of aMSN.
You created this System-Icon for Quick-Contoll the Account, but maybe in future you will put it into the Dock-Context Menu of aMSN if you are able to do something like this, in my opinion it would be a great feature.
I'm sorry if understanding me is not easy for you, but my english is not very well.