Certainly. I've overall been happy with slush's pool, but this is why I'm thinking about switching to another pool.  Here are the results from "ping -t stratum.bitcoin.cz":

http://i.imgur.com/KpwMZwH.png

The time-outs happen regularly.  The problem is NOT with my own internet connection.  I had another ping session running simultaneously (ping -t stratum.btcguild.com), and BTC Guild only had one time-out the entire time.  My location is USA.