I'm on H1B visa and meet the SPT, my sister is on F1 for the whole year 2010.

Can a resident Alien who is on H1B claim a dependent as a qualifying relative (sister) who is on F1 status (non-resident alien)?

Article 501, says they have to be US Citizen, resident or a National. If that is the case, how is a guy in H1B claim his wife or children who are on H4 visa, since they are also not citizen, reisident or nationals or even somebody who is on B1/B2 status?

No, you can not claim any one on F-1. Dependent must be resident of U.S. and F-1 is exempt from residency for 5 years.

H1B (who is resident) can file joint return as residents and claim his/her child even when spouse has never been to U.S. Your U.S. Tax Return: Filing Status for Married (http://taxipay.blogspot.com/2008/02/filing-status-for-married.html)

As MukatA says, the wife NEVER has to set foot in the U.S. if they are filing jointly.

However, the children MUST be resident in the U.S. for at least ONE day in the tax year, or they cannot be claimed.