On my curve 8900 with Tmobile - when I try to connect to app world it "Fails to Transmit". This is on BIS, not BES - I've tried the deleting the IPPP trick, no go. Wiped the phone, checked permissions and set to full, etc. No luck.
Facebook does something similar: "Cannot establish connection to facebook server". Tmobile has been useless and rude. Anyone able to help?