You can see the release history at http://gcc.gnu.org/releases.html

Here's number of releases per year (from all branches):

  - 2011: 6
  - 2010: 7
  - 2009: 5
  - 2008: 5
  - 2007: 5
  - 2006: 4
  - 2005: 6
  - 2004: 7
  - 2003: 5
  - 2002: 5

So at a high level, it doesn't look like the GCC release frequency has changed much in the last decade.

The actual count of releases hasn't been much higher than normal. But recently a number of previously more experimental or controversial features have been released. IMO, the main one that likely wouldn't have been released without the Clang/LLVM pressure is the plugin interface that has been around in branches for many years.

I don't think it has (or will) make a huge difference - gcc has always been competing with commercial compilers (and to a lesser extent, open source compilers like pcc) so it's never really had much of a reason to stagnate.