I'm a Java developer using Java IDEs like IntelliJ IDEA, eclipse and NetBeans. They all use "Ctrl+Space" to bring up context help in the editor. A function that is used quite often.
I just upgraded to VMWare Fusion 5. It unfortunately hijacks "Ctrl+Space" to bring up the currently selected virtual machine menu. So while VMWare Fusion 5 is running you can completely forget about "Ctrl+Space" in your Java IDE. Even if you java IDE is the activa application VMWare will popup its virtual machine menu. I have also found no way to reconfigure this keyboard combination in VMWare Fusion 5.
I have filed an issue on this, but it will probalby take time to even get them to understand the problem since I have to go though their non english speaking support in some low paid place in the world.
So if you are a Java developer and cannot consider changeing the "Ctrl+Space" in the java IDE to something else, then life is going to become very difficult if you upgrade to VMWare Fustion 5!
I'm personally starting to consider Parallels as a way out of this problem.