Someone uploaded this hacked version of adobe flash deb package. It appears to contain both original adobe flash that comes with N900 and the leaked 10.x version of adobe flash but it also seems like there are a few other issues:
1) The installation will take place on rootfs, which means you'll need something like at least 10MB free.
2) There's a red rectangular mark on the top left corner of the video window whenever the leaked 10.x version is used. This is to probably signify that it was a beta release and not a full release.
3) tweakflashplayer will complain and quit if it founds out your adobe flashplayer is not the original maemo version as it goes by filesize checks.

Anyway, here's the link: http://www.mediafire.com/?4riuz660b0t23tp