I just moved from Tucson to Phoenix and am renting an apartment. On my lease, I am being assessed a 2% tax every month on top of my rent. Can I itemize this monthly assessment and claim it on my taxes as I do with my mortgage interest?

Is this a city tax ? not having lived in Phoenix I have never heard of a rent tax before

Yes, city tax; there are different rates for the various cities surrounding Phoenix. Tempe has a 1.5% tax on rent, glendale 1.35%, etc. But I lived in Tucson and didn't see this tax. So it must be with the Phoenix Valley area. My trash and water services have a "conservation" tax (which I find funny b/c recycling is not an option in Phoenix apartment complexes)...tax, tax, tax...

Yes, you COULD deduct the tax under the sales tax option as an itemized deduction.

Unfortunately, it is likely that your standard deduction (which will be about $5,500 in 2008) will exceed your itemized deductions, which has the effect of denying you the deduction.