I hacked around with Beats a bit and got quite a nice osu! mod implemented. Pretty much instead of having the notes scroll down as arrows in normal StepMania-style, the notes appear as tap-able circles in random locations on the screen. The circles fade in with a focusing ring around like in osu!. Tapped notes will turn into a explosion/shout-box image while a missed note will turn into a red X. Currently the co-ordinates of these taps are randomized but will actually follow actual patterns in the future (Matt is currently working on an arc-pattern generator). No slides/spinners/etc. yet (its just simple timed taps) but I may try to implement that later by hacking up what is used for StepMania-style holds.
The structure/backbone is there and close to ready for an actual osu! clone - one step at a time though xD. Support for osu! beatmaps (.osz format) is planned, but probably not before the major Beats 1.5b release (for which I still have to stop slacking off on adding .dwi support). The major barrier would really be me not actually understanding what I'd be parsing - for that, I'd have to play osu! a bit more

For those who are curious and anxious to test things out on their own Android phone, you can grab the latest development build here:
Note that the development build uses a different signature, so you must first uninstall any official release before trying the dev build. The development build also includes a lot of (it's pretty much like 1.4.9/pre-1.5b), some of which aren't 100% complete yet (no hitbox graphics have been added yet, for example, so to see the hitboxes for the different tapbox layouts, you must enable 'Advanced Settings > Debugging > Tapbox Debugging'). When they are ready, however, you can look forward to an official Beats 1.5b release ; )
The current discussion thread on the osu! forums can be found here:
~Keripo