Just got a v1 e280 on ebay. Using a macbook running leopard here. I tried rbutilqt.app with mixed success - it runs fine, recognizes the player and everything, seems to be working, gives finished messages when I try to install stuff, but the only thing it seems to have done right is patch the boot loader. It also created the .rockbox folder, but then didn't load anything into it for some reason. I don't know if it's a leopard related problem or not, but that'd be my first guess. Anyway, patching the bootloader is the only hard part, and doing the rest manually was no problem.
I also have winXP running in vmware fusion, and the win version of rbutilqt seems to work fine in it - I was able to use it to load all kinds of extra themes.
Bottom line - the thing works great with this mac, no problems that aren't unsurmountable.