Sorry for adding more confusion to the pot about all these release dates but just mailed HTC this morning and got this reply.
Thank you for your enquiry about 2.1 update
Some of the phones in our Android line up including your Hero are due to receive an upgrade, and it is scheduled to be released starting at the end of April. Your phone should be upgraded Over-The-Air. You can expect a pop-up message on your phone when connected to the internet once it is ready. When the upgrade is ready, we will notify you via our website and on various social media networks including Twitter and Face book
If these steps have not helped, please let me know by responding using the link provided and I will be happy to check again for you.
Best Regards
HTC customer support team
HTC Corp. Global Service Division