Had anyone noticed a memory leak?
NBES process eats it up.

I reboot the server - all is well.
After about a week the error logs start reporting and "out of memory" error on the mobile data service. All functions work but the error continues once every 20-25 minutes until I reboot.

I had the same 'out of memory' error on BES 4.0 for Exchange. Simply stopping and restarting the MDS service fixes that issue though - no downtime for your BES.

But yes, it is a memory leak. I'm not sure if its known though. I've been running BES 4.0 for about three weeks now and only have seen it once.

I only have about 10 users on the BES 4.0 server (in test; 3.6 in production), and only about 4 need MDS, so I disabled it for the others at the same time I first saw the error.

Moved to BES forum

Make sure you close the BlackBerry Manager on your server and never leave it open. It will leak some memory over time.