Is it possible for a temporary (non-citizen) long term (leaving in 2 years) resident in Canada to obtain RRSPs? Is it advisable?
In general, if you are paying taxes in Canada, you are eligible to contribute to an RRSP. That said, it still may not be appropriate.
If you are only here two years, then you will not accumulate much contribution room. Then once you move away, your options become more limited. Most brokerage accounts in theory require you to be resident in Canada in order to issue instructions - an odd holdover I agree, and one that with internet connections may well not be easy to enforce.
I presume you are looking for some kind of tax shelter? I would suggest you look at the new-ish TFSA (Tax Free Savings Accounts) as a possible alternative.
Even more specifically, if you are making enough that any of these matter, then consulting with a tax accountant is likely money well spent. They will be much better able to advise you about your specific situation with respect to accounting for taxes between your home country and your temporary status in Canada.