  We report on the aperiodic X-ray timing and color behavior of the accreting
millisecond X-ray pulsar (AMXP) IGR J17511-3057, using all the pointed
observations obtained with the Rossi X-ray Timing Explorer Proportional Counter
Array since the source's discovery on 2009 September 12. The source can be
classified as an atoll source on the basis of the color and timing
characteristics. It was in the hard state during the entire outburst. In the
beginning and at the end of the outburst, the source exhibited what appear to
be twin kHz quasi periodic oscillations (QPOs). The separation \Delta \nu
between the twin QPOs is ~ 120 Hz. Contrary to expectations for slow rotators,
instead of being close to the 244.8 Hz spin frequency, it is close to half the
spin frequency. However, identification of the QPOs is not certain as the
source does not fit perfectly in the existing scheme of correlations of
aperiodic variability frequencies seen in neutron star low mass X-ray binaries
(NS LMXBs), nor can a single shift factor make it fit as has been reported for
other AMXPs. These results indicate that IGR J17511-3057 is a unique source
differing from other AMXPs and could play a key role in advancing our
understanding of not only AMXPs, but also NS LMXBs in general.
