Not really, the 'early 2012', 'mid 2010' etc. dates refer to the release of that particular model. Any macbook air bought since the refresh would be considered a 'mid 2011'. Including any that were purchased in early 2012.
By that definition, if I purchase a 2008 MBP today, would that make it a "Early 2012 MBP"? Certainly boosts the resale value
No it's not. The naming conventions that people adhere to are to refer to a model by when it was released and not when it was bought. Therefore the 2011 MBA is always the 2011 MBA, even when it was bought in 2012. This helps to alleviate confusion.
I laughedby that definition, if i purchase a 2008 mbp today, would that make it a "early 2012 mbp"? Certainly boosts the resale value
You would think if you did that on a macbook pro 13 inch it would keep it from losing battery charge when doing intensive tasks as it does on the original charger...because it has a higher wattage, it should supply more...It probably isn't the case but it would be logical.In regards to the original question: No this won't work.
You can use a higher wattage adapter with a Mac laptop but not a lower one. So you can't use the 45W Air adapter on a MacBook which normally needs a 60W adapter.
From the relevant Apple kBase Article:
Power adapters for Intel-based Apple portables are available in 45W, 60W, and 85W varieties. Although you should always use the proper wattage adapter for your Apple portable, you can use an adapter of a higher wattage without issue.
For instance If you have a MacBook (13-inch Late 2009) that normally uses a 60W adapter, you can also use an 85W adapter with that computer. You would not use a 45W adapter with that computer; it would not provide enough power for that MacBook. Using an adapter of higher wattage than the adapter that came with the computer will not cause the computer to charge more quickly or otherwise operate any differently than using the adapter that came with the computer.