damn, i was late.
it's an octatonic scale, pretty clearly, and it's refered to as the "3 4" octatonic scale. there are three scales - 1 2 (root is C#, starts with a half-step), 2 3 (root is C and starts with a whole-step), and 3 4 (root is C#, starts with a whole step)- depending on whether the scale starts on C or C# (eventually, you have to wrap it around until you get a root) and the absolute pitches of the second and third notes. that is, if i remember my post-tonal theory well enough. so, for example, this 3 4 scale would be written as C# D# E F# G A Bb C C#. an interesting note about octatonic - it's the second most widely-used scale that requires the use of both flats and sharps in the same scale, with harmonic minor scales being the most widely-used.
as siriusbeatz said, it's basically a scale that can be used over diminished chords (like the ii0 in a ii0 V7 i progression, 2-5-1 in minor). the term octatonic can technically be used with any scale that's based around eight notes plus the octave, so even a major scale with both minor and major 7ths would be octatonic. the tonality created by a whole-half scale, however, is refered to as octatonic exclusively.
the scale itself is finding a lot more usage in modern tonal composition, however, as it allows for a more complex-sounding scalar figure than a traditional major or minor scale. unlike traditional seven-note scales, it also allows for two beats of sixteenth notes in a run with the scale ending on the top note, as opposed to the septuplet that is often used for the same figure with major or minor scales.