Ubuntu on Arm

Does ubuntu on Arm work with Raspberry Pi

No. Ubuntu doesn't support the Pi's ARM version, and never will.

Actually, that's not quite right. It worked up to version 9.4

So, you can, of course, still install that version.

Of course, there may be grubby details involved in getting from whatever it is you download (presumably, a .ISO [*] file) to getting it running on the Pi. I hold no brief for that.

[*] Yes, I really mean .ISO file - I am not using it as a generic term for archive file.

is there any one that is working on a ubuntu version that is working on the raspberry pi

No there is not.
Canonical aren't interested in doing it, and i don't think anyone else has seen the need to try it. At least nobody on this Forum has announced something like that. It would be a lot of work, and probably would also cost a good sum of money. For more information how much money it could include you could read this Thread in the Raspbian Forum.

Ok

[plugwash]

My big question would be what is the point? Afaict the bulk of ubuntu's customisation effort goes into heavyweight desktops (gnome3, unity etc) which would be of little use of the Pi.

Someone's got Ubuntu 12.04 Running on a MK802. It's more expensive than a Pi (£48 compared to the Pi's £30), but if you only value your developemnt time at £1 / hour, you'll still come out ahead going down that route rather than trying to shoehorn a version of Ubunt onto a Pi.

[plugwash]

£48 compared to the Pi's £30.

It's listed at $70 (which google shopping translates to £47.09 but your credit card provider is likely to translate to something higher than that) on aliexpress but it is being posted direct from china and it's above the threshold for VAT. So you may well get charged VAT and brokerage charges on top of that (OTOH the supplier may lie on the customs form or the package may simply slip through)