1. Before the draft, picks have no salary cap value.
2. Unsigned first round picks are included in team salary immediately upon their selection in the draft. They count as 100% of the scale salary for that pick, unless there is a verbal agreement for a higher salary.
3. Once a first round pick signs a contract, his actual salary is included in the team salary, of course.
4. If a first round pick signs with a non-NBA team, his scale amount is excluded from the team salary on the date he signs his non-NBA contract or the first day of the regular season, whichever is later.
5. Unsigned second round picks are not included in team salary.
http://www.cbafaq.com/salarycap.htm#Q50