Today, 31 August 2012 is Purnima Vrat. It is Adhik Bhadrapada Purnima, Full Moon Adhik Maas (Extra lunar month) in Hindu calendar.
This Purnima begins at 8.12 PM on 30th August and ends at 7.28 PM on 31st August.
Adhik Bhadrapad Purnima brings the end of Adhik Maas as per the Hindi calendars followed in North Indian states like Haryana, Himachal Pradesh, Madhya Pradesh, Uttar Pradesh, Bihar, Uttarakhand, Jharkhand, Rajasthan, Chhattisgarh, etc..
The following day of Adhik Bhadrapad Purnima marks the end of Shukla Paksha in Adhik Maas as per Marathi, Gujarati, Telugu & Kannada calendars.