I had a little problem when installing today Play! framework in ArchLinux.

Doing a strace I realized what happened:

rt_sigaction(SIGINT, {0x438d50, [], SA_RESTORER, 0x7f79584319f0}, {SIG_DFL, [], SA_RESTORER, 0x7f79584319f0}, 8) = 0
wait4(-1, java.io.FileNotFoundException: /opt/play-framework/framework/sbt/boot/sbt.boot.lock (Permission denied)
	at java.io.FileOutputStream.open(Native Method)
	at java.io.FileOutputStream.(FileOutputStream.java:212)
	at java.io.FileOutputStream.(FileOutputStream.java:165)

So You could just give permissions to that file...

sudo chmod 666 /opt/play-framework/framework/sbt/boot/sbt.boot.lock

You could have the same problem when creating the project, the bad solution is using sudo to create it, the good one is giving permissions to play-framework directory to create the project with the correct ones.

And that's all! Happy coding! :-)