Every contract is different, so you need to look up the Economic Viability clause in your Purchase and Sale Agreement and see what it says. It will usually have a date (eg. July 31, 2009), and then another date maybe 3 months later (eg. October 31, 2009) that the developer can unilaterally extend to without your consent. Anything past this final date needs your consent and they have to give you the option of agreeing to an extension or voiding the contract and giving your deposit back (plus interest - although it'll be a pittance). I would guess that your final EV date would be sometime this year. If 2011/12 is your latest date to move and you really like Liberty Village then I'd look at CanAlfa's properties as both Bliss and Liberty Towers will be built by then (and are now offering unadvertised incentives and will probably be very amenable to price negotiations) and maybe even Liberty On the Park. I'd also look into the Liberty Market Lofts - they're really cool and quite good as well for the price/sq foot and seem to be in a better position to actually get built. Toy Factory has some good layouts as well and will probably have some good resales going on. Do your due diligence though and don't take my word for it. Best of luck!!
Sorry Mods, I know this is real estate in the more architecturally oriented thread. Do what you must