Well I have searched far and wide for some solutions but I decided to take all the problems I have had into one.
First I have a 27" Apple iMac (Late 2009 Release) running a intel i7, 4GB of RAM, and ATI Radeon HD 4850 card with the standard airport extreme 2 which is running MAc OS X Lion (10.7.4) I checked the hardware support and Ubuntu seems to be ok after some tweaking.
So here is what I did in the exact order based on some lengthy research.
First I downloaded rEFIt (version .14) and installed it. I did a quick halt and reboot and it work.
Next I wasn't sure whether to trust ubuntu to parition my main drive or handle it myself. So I decided to go for the self partitioning. Did you know that partitioning on Lion is not like partitioning on Leopard?
I ended up reparing the disk and rebooting into recovery mode and making the partitions there. I have a 1TB hard and I slipt it up as so (Approx.) MacOS = 575 Exfat(I called it Data) 350 and 75Gb Free Space.
Next I downloaded the 64 bit version of the newest ubuntu release Ubuntu 12.04.iso and burnt it to disk using the slowest write speed.
Next I inserted the disk and restarted the and held "C" it booted to from the CD and I was at the first menu in the Ubuntu phase. I first selected the Language then Install Ubuntu. Immediatly the screen went black but the disc was still reading. I immediatly realized this was Either a GUI issue or a Display issue. So I did some research and found out about the 'nomodeset' I did that and the install ran well. At least I thought. I restarted the Mac and waited for the EFI Boot menu or Grub menu. Nothing. So I shutdown and powered up again and this time held 'Alt' the menu came up and I selected the Windows Disk and then it went to the grub menu and I then had the choice again. I chose Ubuntu obviously. Purple screen popped up thenn! Command Line. I figured the disk failed and so I connected to my wifi and then proceed to update and then install the ubuntu desktop. I tried running the startX command but got nothing ESC and f6 failed me and so I shutdown. When i rebooted the mac goes straight to OS X. Its quit bothersome and I am surprise that this is this difficult. I suspect the Recovery Drive Lion create is to blame.