Make no mistake, at least based on the Instagram pic posted by Zac Altman which clearly shows an iOS 6 banner. the big iOS update will definitely be unveiled at the Apple Worldwide Developer Conference 2012 next Monday. iOS 6 is expected to feature an improved UI (more silver accents) and one key change would be the utilisation of OpenStreetMap with 3D (yes, officially ditching Google Maps).
Source: CultofMac