I know this is an old thread but I'm having trouble compiling the core in ubuntu. I followed this walk and got an error on the third command. I also tried to follow the more recent guide here
http://bitzuma.com/posts/compile-bitcoin-core-from-source-on-ubuntu/ and ran into problems as well. I usually have a problem when I enter the command ./autogen.sh. If anyone can tell me what I'm missing I'd appreciate it. I'm pretty sure I have all the dev tools necessary and had no problem unpacking the berkely database. Thanks