I use two transports, deepdarc.com for AIM and jabber.anywise.com for MSN.
Deepdarc stopped work for me and 3 others. I registered AIM on bgmn.net for now. I just checked and the deepdarc transport is back online, but can't register to it. <shrugs>
I quit using MSN transports altogether after my contacts where complaining of constant pop-ups.