The new RedHat 6.1 bootnet.img installer does not support FTP network installation if PCMCIA support is needed. Instead of asking for the pcmcia.img it asks for a network card driver. This makes it virtually impossible to install RedHat 6.1 on a notebook.
I am sorry for being so stupid! I should have noticed that PCMCIA installation has to be done with pcmcia.img. I just overlooked the fact while browsing through the README file. However, since I know of four different people who made the same mistake, I would suggest to change the name of the pcmcia.img to something like btpcmcia.img or bootpcmc.img, since it is somewhat misleading, when a file with the same name as in the 6.0 release has a completely different function.