I cannot swear by it, but it seems that after upgrading to CM7.2 from 7.1 my Wifi is not working as expected. While at home all appears to be fine, but I notice that Twitter, GReader and GMail never update. As soon as I turn off WiFI and go on cellular data, I'll receive my notifications. Now I leave my phone off of WiFI to ensure that I receive my messages.
WiFi was working just fine under CM7.1. I can confirm that once I cycle WiFi it appears to work but for how long I don't know.
Baseband - T959TLJL3
Mod Version - CyanogenMod-7.2.0-captivatemtd
Build Number - GWK74