I don't normally follow Linux kernel development, but I was pleased to hear (via Andres Freund) that the Linux kernel developers have committed a series of patches by Andi Kleen to reduce locking around the lseek() system call. As I blogged about back in August, PostgreSQL calls lseek quite frequently (to determine the file length, not to actually move the file pointer), and due to the performance enhancements in 9.2devel, it's now much easier to hit the contention problems that can be caused by frequently acquiring and releasing the inode mutex. But it looks like this should be fixed in Linux 3.2, which is now at rc1, and therefore on track to be released well before PostgreSQL 9.2.
Meanwhile, we're gearing up for CommitFest #3. Interesting stuff in this CommitFest includes Álvaro Herrera's work on reducing foreign key lock strength and a PostgreSQL foreign data wrapper (pgsql_fdw) by Hanada Shigeru. Reviewers are needed, for those and many other patches!