Removing the widget solved the problem for me. Before I did that it stopped every few days or less. Now it has been great for more than a week so far. Someone said they didn't think that was it but I haven't changed anything else. Maybe worth a try and report the result if you are using the widget.
Not using the widget here I removed a bunch of apps as well to see but no luck unfortunately. I've just gotten used to hitting the refresh button which stinks.
Think I found my issue here at least and wasn't until I saw the thread about the Wifi icon color. With 3.2 Gmail is pretty stable for me via Wifi at home or 3G. However at work it's another story with very laggy/sluggish Gmail. Well at home the Wifi icon color is blue which from I understand means it has access to the Google servers. However at work, which is probably proxyed, it's most definitely grey with intermittent blue during the day. I'm not sure if there is a poll interval with the Gmail app, but that is most likely the problem as any real time communication is not happening due to probable filtering at work.
I removed a bunch of apps as well to see but no luck unfortunately. I've just gotten used to hitting the refresh button which stinks.