It depends on what numbers you are interested in. There are two numbers that are common to use
Unemployment number and workforce participation, the first one went down but the later one also went down.
Unemployment number This is the number most commonly used and the definition varies what constitutes "unemployed" from country to country. In the US the current number is 7,8% (September) in August it was 8,1% (August) 8,3% (jul)
But in the same time "The U.S. labor force contracted by 368,000 in August 2012 compared to the previous month, reaching 154.6 million. The share of the working-age population, 16 years old and over, that was currently employed or unemployed (i.e., the labor force participation rate) was 63.5%."
So to be clear to be able to get a lower Unemployment number 368 000 people had to stop looking for jobs. All in all this is a bad sign for the US economy.
But sins this is the official way U.S. Bureau of Labor Statistics counts and has not changed this last few month the answer must be: No the current administration did not manipulate the numbers. They told the truth but not the whole truth.
Sources: http://data.bls.gov/pdq/SurveyOutputServlet?request_action=wh&graph_name=LN_cpsbref3 http://www.ilo.org/washington/ilo-and-the-united-states/spot-light-on-the-us-labor-market/recent-us-labor-market-data/lang--en/index.htm