@zepretender:
I think you should do what Jaloon said, try using lMule, xMule or xMule v2. As for mldonkey, there's a
new GUI being developed. AFAIK it's already working, haven't checked it.
Don't worry for now about the new network, even when it's ready, I don't think people will just leave the servers really soon. The major problem with mldonkey is that it seems almost abandoned, they did a bugfix release some time ago, but I haven't seen a major release for almost an year, I think. Keep an eye on alternative projects at sourceforge.net, there's some work on both Java and C# clients out there.
@Unknown1:
WINE can only run Windows binaries on x86 machines. It's an alternative implementation of some of the Windows' APIs, not an emulator of the IA-32. To run eMule on another architecture, you'll either need a port of it, or an emulator or simulator of the IA-32 and a copy of Windows installed on it. The way to go is using some other port that does not relies on Windows APIs or to try to compile both WINE and eMule natively on a Mac, then link them, if they actually compile.
I never compiled eMule and linked it against WINE on Linux (on my x86 machine), but if it can be done, chances are that it may work on PPC Linux and MacOS X too.