Can’t say one could determine definitively from all of the above, but regarding the primary point of the post, the limit that you and your spouse can be gifted (without tax consequences) in 2010 is $52,000. The limits are per donor and per recipient and is $13,000 this year. So, you can receive $13K from each your FIL and MIL and your spouse can do the same.

Also, it’s important (for your in-laws) to understand that the gift payments themselves are not tax deductible. The gift money will not be taxed, but they cannot reduce their taxable income by the $52K.

Anything above that ($48K in your scenario) is subject to the lifetime estate tax exclusion ($1 million at the moment) and your in-laws can decide whether they want to pay the taxes now or later. Later’s decidely better if they’ll come in below a million, but that’s probably not too likely. Otherwise, I believe there are pros and cons that they should discuss with a qualified tax/estate planner type.