I am running a Sprint Pre with 1.4 and about 30 patches at the moment. I haven't been brave enough to overclock my Pre however, even though I've heard that it helps to cure the Too Many Cards Open problem that's been plaguing us since the 1.4 update.
This past Sunday I was busy using my Pre when I stated getting the Too Many Cards Open notice. So I closed out a card or two, opened Jstop did a Garbage Collection and kept going.
After about a half an hour it came up again so I repeated. Over the next few hours I ran Garbage Collection about 10 times and even did a Luna Restart to no avail.
Now not only was I getting Too Many Cards but also the Memory Critical notification.
Finally I decided to go ahead sit through the Full Restart, of about 2.5 to 3 min or so.
It is now Wednesday and I haven't had the dreaded message yet. Though it's a bit inconvenient Rebooting seems to be a good fix.
I just wanted to share this.