Latest revision is 2.73.xxx.xx The first step is check with your network provider. If nothing is available there then check HTC - Support - HTC Hero.
When I try put in my s/n it says 'Sorry, this software download is not suitable for your device.' What can I do now? Sorry for double post, I didn't realise.
The software you are trying to download could be the stock htc software. Have you tried your network providers download?
They do not have one on their website, I just got my phone replaced yesterday for not having the latest software, yet I got it back with 1.0.0.A6288