* GDP, jobless claims data due
* Oil prices dip, remain near recent multi-month highs
* Guess shares rally after strong sales
* Vodafone in talks with Verizon to sell out of U.S. venture
* Futures up: Dow 16 pts, S&P 4 pts, Nasdaq 12 pts
NEW YORK, Aug 29 (Reuters) - U.S. stock index futures edged up on Thursday on growing signs a timeline for launching a Western military strike on Syria could be delayed, though caution lingered across markets.
* Any retaliation over the Syrian government's alleged chemical weapons attack on civilians could be complicated not only by the U.N. weapons inspectors' continued presence in Syria, but by the Obama administration's efforts to coordinate with international partners and growing demands for consultation with U.S. lawmakers.
* Adding to the concern, Russia, Syria's powerful ally, is sending two warships to the eastern Mediterranean, according to Interfax news agency.
* U.S.-traded shares of Vodafone Group PLC rose 8 percent in premarket trading after the company said it was in talks with Verizon Communications to sell its 45 percent stake in their U.S. joint venture, Verizon Wireless, for what a Bloomberg report said would be about $130 billion. Verizon shares rose 4.2 percent.
* S&P 500 futures rose 4 points and were above/below fair value, a formula that evaluates pricing by taking into account interest rates, dividends and time to expiration on the contract. Dow Jones industrial average futures rose 16 points, and Nasdaq 100 futures added 12 points.
* Brent crude fell 0.7 percent as traders reassessed supply risks emerging in the Middle East, but remained its highest since February.
* Data due at 8:30 a.m. EDT (1230 GMT) includes the second estimate of gross domestic product growth for the second quarter. Economists in a Reuters survey forecast a 2.2 percent annualized pace of growth compared with 1.7 percent in the first estimate. Jobless claims for the latest week are also due.
* Guess Inc shares jumped 18 percent in premarket trading a day after its second-quarter results beat Wall Street estimates, bucking a trend of falling sales for apparel retailers.
* Fast-food workers, including those from McDonald's , Wendy's Restaurants, Burger King Worldwide and others across the United States, are expected to stage their largest strike to date on Thursday in an almost year-long campaign to raise wages in the service sector.