General rules of the US Senate:
http://rules.senate.gov/public/index.cfm?p=RulesOfSenateHomeThe rule used in "Mr Smith goes to Washington" still exists (Senate Rule 19):
1. (a) When a Senator desires to speak, he shall rise and address the Presiding Officer, and shall not proceed until b]he is recognized, and the Presiding Officer shall recognize the Senator who shall first address him. No Senator shall interrupt another Senator in debate without his consent, and to obtain such consent he shall first address the Presiding Officer , and no Senator shall speak more than twice upon any one question in debate on the same legislative day without leave of the Senate, which shall be determined without debate. The above is rarely used, but still can be used.
Rule XIX:
http://rules.senate.gov/public/index.cfm?p=RuleXIXWhat most people call a Filibuster is Senate Rule XXII, Section 2, Paragraph 2:
"Is it the sense of the Senate that the debate shall be brought to a close?" And if that question shall be decided in the affirmative by three-fifths of the Senators duly chosen and sworn -- except on a measure or motion to amend the Senate rules, in which case the necessary affirmative vote shall be two-thirds of the Senators present and voting -- then said measure, motion, or other matter pending before the Senate, or the unfinished business, shall be the unfinished business to the exclusion of all other business until disposed of.{/i}
Notice the wording, the Senate can go on to other matters, but does not have to if the leadership wants to stay on that subject. Since the rules were changed in the early 1970s (from 2/3rd of the Senate to 3/5 of the Senate, i.e. from 67 Senators to 60 Senators), This was the same rule as in 1964, but in 1964 the Senate decided to continue the actual debate NOT go on to other matters.
In simple terms, the Senate can still "debate" the bill and if the leadership wants to continue that debate it can do so. It ties up the Senate for nothing else gets done, but that is what the LBJ and the Senate Leadership decided to do in 1964. The Senate leadership has refused to do so since 1964, it has always gone on to other business or continued the debate to another date and time (Which never arrives).
Thus the Senate can do a 1964 type Filibuster, the key is for the Senate Leadership (and this needs support from Obama) to decide to continue the debate on and on and on till the GOP finally gives up.
Rule XXII:
http://rules.senate.gov/public/index.cfm?p=RuleXXII