For those interested, here's a build of Open remote play running on the N900: kakaroto.homelinux.net/~kakaroto/n900/orp/
Just follow the instructions... I didn't bother creating a .deb, so just scp those files somewhere on your N900 (like /opt/orp) and run /opt/orp/orpui directly through xterm or using ssh.
It works, but it seems that the rendering with the SDL is extremely CPU hungry so it's slower than bearable, not usable at all actually... The UI also needs some work. I had to disable the bitrate setting in the profile edition page, because it didn't fit in the resolution of the screen, and there was no scrollbar, so it was impossible to save the ip address of the ps3.
The input key bindings also need to be changed since they refer to non existing keys on the N900 keyboard (F1/F2/F3/F4/Escape/etc..). I tried to take a screencast, but it didn't work because the screencast couldn't capture the rendered frames, it just showed a green frame instead of what I was seeing.
I hope others will get the motivation to improve this. Enjoy!