On a house purchase, any points would be deductable at one time. (Sorry, I don't remember where that gets accounted for on the schedule A)
If you paid points for a refinance, the amount of the points would be amortized over the term of the mortgage. So, if you paid $1500 in points, for refinancing into a 15 year term, you would be able to deduct an additional $100 per year in additional interest. Now, if you sell your house after 5 years, then I believe you can take the remaining $1000 in a lump sum deduction.
Now the fine print...I am not an accountant, so maybe a tax person or accountant type will add their 2 cents worth. I am a refinancing queen, so have had lots of experience with the points thing.