I bought a HTC S730 (european) and also have the memory problem. So contacted HTC support several times and send emails. They came back explaining that the phone has ram and rom and how the birds and the bee's work. After several emails explaining the ram problem, memory going down after using the phone, they finally came back with the answer: Please backup your phone-data and hard reset the phone!!!
Well, after this 'great advise' I thought I'd better call the support line. After an interrogation and asking my imei number from the phone they finally wanted to answer my question about the memory.
Then they said that I installed too many programms on the phone and that was giving the problems, when I responded I had nothing installed they told me it was because of the too many big emails that were in my inbox. I assured them that there were only a few and this couldn't be the problem, then they asked me to wait........
After 5 minutes holding they said they had a lot of S710's lying around and they all work fine and told me that is basically the same phone.
I managed explain them why it was not and to please check on a s730, then they told me that they did not have one. So they asked me to hold again......
When she came back on the line after another 5 minutes they told me that there were no firmwares in the works as this was not a known problem to HTC and she couldn't make a note of it because this problem was not acknowledged by HTC. I asked her to at least make a note of my complaint, but she answered she could not leave support-tickets open...
She also added not to worry, because a technical person in her team told her that even if the memory in the task manager shows 9mb free, the missing mb's are actually there, only the task manager doesn't refresh it properly.
Now my hope is, maybe somebody on this forum has a contact in HTC higher up that actually has some Idea if this problem will be addressed or officially will be real in the near future.
Hoping for some positive news,