A piece of work I've been doing has involved taking a cursory look at Celona Evolve, though sadly I haven't been in a position actually to give it a go.
Coincidentally, this week Bloor's Philip Howard has written about it at IT-Director.
For the Oracle-ite, it's positioned in a similar market segment to Oracle Data Integrator (formerly Sunopsis); providing traditional ETL but also talking up continuous (or "progressive") integration (EAI / SOA / EII - take your pick of acronyms).
So far, successful references for Celona are hard to find - always a problem for startups. And it's a UK company; my personal experience says that tends to be a disadvantage too. You may get a few good early adopters over here, but going to the States can be a killer. At present the product seems to rely heavily on Celona's accompanying services; they won't be able to grow properly until either the product is easier to use, or there's a large independent base of Celona skills in the market (as there is for other tools like Informatica, OWB, etc).
They're obviously gearing up for a more public stance; they "launched" on 8th May (hence the analyst briefing). Good luck, we'll see how things progress