While many players, including me, are nowhere near the cap of 650 pets, a cursory glance at sites like warcraftpets.com indicates that there are many players rapidly approaching the cap, if not quite there yet. The top collector on their rankings has 567 unique pets, not to mention any duplicates. Indeed this site shows that there are currently 580 battle pets available, and we already know of several new pets being added with 5.4, so this increase in the cap is welcome indeed.
A quick glance at my character reveals that, on the account with the most pets, I have a paltry 103. There is little to no likelihood of my troubling the 650 pet cap at any time soon. Where are you with your menagerie?