This probably isn't what you want to hear, but talking to friends who live in Dubai, they're saying that very few of the ex-pats are buying now. From their point of view the prices are 'un-proven', as they can literally go on building as far as the sand goes! A few have raised concerns about the build quality, 1 person who had bought a villa less than 5 years old has just had it condemned, and it needs to be rebuilt!
Finally a lot of the money that was made in Dubai has been through flipping properties, the first range of houses / appartments are only now being completed, so it a bit difficult to value them realistically.
There is a lot of building going on with the infrastructure just keeping up, but Business Post had a good article a while back about the potential issues with the Palm area, as they increased the number of units being built but haven't upped the number of roads. And this developments is feeding out onto one of the main highways (sheikh zayeed road I believe).
On the plus side there is a push to grow Dubai, I think they are talking doubling the population over the next 10 years (i'm open to correction on this one). There is currently a strong rental market, with the rents currently on the increase, and many ex-pats do get rental allowances while there (many of those expats are on 3-5 year contracts), and the norm seems to be paying the rent every 6 months.
Have you visited Dubai? Before making any commitments I'd check it out and see if its where you want to tie up your money.
For developments, check out some of the main builders and developments
www.emaar.com and are the only one I can think of off hand. See what they are quoting, before going looking at the agencies who will get a cut!