Hari Om Namo  Narayana
Today is Vaikunta Ekadasi. Ekadasi means 'the eleventh' in Sanskrit and refers to the eleventh day of a fortnight  belonging to a lunar month. Falling in the moon’s waxing phase in the month of Dhanurmasa (December-January), Ekadasi is synonymous with fasting and abstinence. The Dhanurmasa sukla paksha ekadasi is  called Vaikunta Ekadasi.
However, the  austerity is associated with much deeper aspects. This is  explained in the Padma Puranam (the second amongst the eighteen  puranas), which tells us about the beginnings of Ekadasi with this story.  
During the Krita Yuga, also  termed the golden age, an asura called Muran harassed both devas and  mortals. Unable to bear his tyranny, the devas sought refuge in Shiva.  He directed them to approach Vishnu. Vishnu agreed to help the devas and went  out to battle with Muran. During the long battle, which lasted one thousand  celestial years, Vishnu needed to rest for a while. He entered a beautiful cave  called Himavati in Badarikashrama to sleep. Muran wanted to strike Vishnu while  he was sleeping. 
However, Shakti – Vishnu’s female energy  – emerged out of his body and assumed the form of a beautiful damsel who fought  Muran and vanquished him. When Vishnu awoke he was very pleased and named this  maiden as Ekadasi and granted her a boon. The maiden  said, "O Lord, if You are pleased with me and wish to give me a boon, then  give me the power to deliver people from the greatest sins if they fast of this  day”. Vishnu granted her the boon and declared that people worshipping her  would reach Vaikunta. 
Thus, it is said, was born the first  ekadasi, which was a Dhanurmasa sukla paksha ekadasi. Sages and devout  people have been since, observing the ekadasi vrata regularly. Here, the  demon Muran represents the tamasic and rajasic qualities in us. The import of the ekadasi vrata is that one  can conquer rajasic and tamasic tendencies in us through fasting. This helps us  reach our ultimate destination, Vaikuntha, which is the place or stage of no ‘kuntitha’ or dullness, stupidity and misery. 
It is also said that on this day the ksheerasagara  manthana (churning of the ocean) took place and the nectar of immortality  (amritha) was distributed to the gods. This divine event is interpreted in the  following manner. The ocean of milk is the human heart filled with satvic  tendencies (kindness, purity and goodness). However, in all of us there exist  both types of inclinations, good (devas) and bad (asuras). Only Sadhana or the churning process will throw out the poison in us and we can procure the  sweet nectar, which will liberate us from the cycle of birth and death.  Shaivaites call this day as Nanjunda  Ekadasi, as it was on this day Shiva consumed nanju, the poison that  emanated from the churning of the ocean.
Some schools of thought believe that Sri  Krishna gave the Gitopadesam to Arjuna on the day of Vaikunta Ekadasi. For the Vaishnavas, it is a very  holy day and should be ideally spent in fasting, prayer and meditation.  Devotees look upon this austerity as a means  to succeed in their spiritual endeavours. To them it is an activity which will  increase their sankalpa (that which is beneficial to them), so as to avoid  activities which are not beneficial to them (vikalpa). Such  austerities make a student of spirituality enthusiastic, positive, serene and  determined. They finally lead to the understanding that all activities must be  only performed for the pleasure of the Lord. Austerity is indeed one of the  four legs supporting religion, the other three being purity, mercy and  truthfulness.
  
  In his Gitopadesam to Arjuna, Sri Krishna describes the threefold path of austerity and  says “deva – dvija-guru-praajna-pujanam-shauchanam-arvajanam-brahmacharyam-ahimsaa-cha-shariram-tapuchyate”,  which means one must worship the Supreme Lord, the Brahmans, the spiritual master, and superiors like the father  and mother. Cleanliness, simplicity, celibacy and nonviolence are also  austerities of the body (Bhagvada Geeta 17.14). Truthful speech, which is not  offensive to others and the regular recitation of scriptures, is austerity of  speech (17.15). Serenity of thought, compassion, gravity, self-control, purity  of purpose, are all austerity of the mind (17.16). 
This threefold path of  austerity, practiced by men whose aim is not to benefit materially but to  please the Supreme, leads to a nature of goodness. Sri Krishna finally says  that penances and austerities which are performed foolishly, by means of  obstinate self-torture, or by destroying or injuring others, are the approach  of the ignorant.
It is also recommended that one must not  perform austerities beyond his capabilities, lest the austerities become mechanical  or offensive.
The Padma Purana says: 
  “ekadasi vrata samam vrata nasti  jagattraye
    anicchaya'pi yat krtva gatir evam vidha'vayoh
      ekadasi vratam ye tu bhakti bhavena kurvate
      na jane kim bhavet tesam vasudeva anukampaya” ,
which translates as: In the three  worlds, there is no kind of fasting which is even comparable to the Ekadasi  fast. Even if one performs this fast without a proper attitude, he achieves the  Supreme Abode. If one fasts on Ekadasi day, with full devotion, what happens to  him by the mercy of the Supreme Lord, I cannot say (the merit he achieves  cannot be described).
While  Vaikunta Ekadasi is observed in all Vaishnava temples, the day is very special  at the Sri Ranganatha temple at Srirangam in Tamil Nadu.  On this auspicious day, Lord Ranganatha in  all His glory and resplendence enters the Parama Padha Vaasal (the gateway to  salvation) at the sacred precincts of the temple at Srirangam, and showers His  blessings and grace on mankind.
In 2004, Vaikunta Ekadasi falls on the third of  January.