The upgrade is advertised on their website.
Here's the link:
Also, it would appear ppl on 750k speeds will be automatically upgraded to 2Mb, and 1.5Mb customers will soon be on 3Mb soonish... Nice!
I grant you that a happy NTL customer would not really have cause to return the NTL site and check for upgrades, but since my first speed increase I check the site every couple of months or so.
Perhaps we should keep this info quiet to keep the contention ratios down ;)