Home Buyer Tax Credit Clarifcations

The recent expansion of the Home Buyer's Tax Credit has created some confusion in the market regarding who qualifies as a "current homeowner". There have been several erroneous descriptions in the press but checking the IRS link to the tax credit http://www.irs.gov/newsroom/article/0,,id=206293,00.html.) one finds the following restriction :
If a homeowner has owned, or had a financial interest in, their principal residence for the last three years prior to purchasing a home that may in all other respects qualify for the Home Buyers Tax Credit, the new home purchase is NOT eligible for the credit. If they owned their principal residence for 5 of the last 8 years (but not the last three years!) then they are considered a "current homeowner", not a first time buyer. In other words if they own a home that up until 3 years ago was their principal residence, but they have not used it as such for the last 3 years, they are considered "current homeowners". First time buyers have not owned a home (I believe that means "any home") in the last 3 years. The difference is that "current homeowners can own or have a financial interest in properties that have not been their principal residence for the last 3 years.
The law elsewhere specifically eliminates using the credit for acquiring investment properties. To qualify, the property MUST become your principal residence (the purchase of a duplex may qualifyfor the credit on that portion of the property that you live in). The restriction described above eliminates the credit on the purchase of any property IF you currently live in your owner-occupied principle residence. Apparently the law is intended to get people back into home ownership, not increase investment purchases or vacation home purchases.
As always, check with your accountant for tax advice on any real estate transaction!