The fuel is a generation that no longer writes checks, said Ben Milne, Dwolla's founder.

"Every institution needs to be looking at offering P2P this year," said David Eads, a senior executive at Kony Solutions, a mobile application platform provider based in Orlando.

"Credit unions know they need to address P2P," agreed Brian Day, an executive with The Members Group, a payments company in Des Moines, Iowa.  "And, I think they need to address it in 2012."

One reason for the urgency is that rumors are swirling that nonbanks, including PayPal and Apple, which sits on billions in cash and has its massive iTunes user network in place, are about to pounce on P2P. There is no acknowledgement of any of this by the rumored parties but those who are hip deep in the service insist that more players will be at the table before long.

Another reason for the urgency is increasing recognition that traditional online bill pay just does not work for casual money exchanges among friends, and co-workers, experts have discovered. Write a $3.50 electronic transfer in bill pay for Girl Scout cookies and what would happen is that a week or so later, the seller would get a paper check in the mail.

With P2P, all that is needed is an email address or possibly a Twitter or Facebook user name or email address and the money moves from the payer's account to the payee.

If it is that easy, why has P2P penetration, thus far, been minimal, a conclusion underlined in a recent ComScore online and mobile banking survey which found that only 26% of those surveyed had any awareness that P2P tools existed. Still, user satisfaction came in at a fairly high 66%.

One issue is the payee experience could stand to be improved, said Anthony Vitale, vice president of information technology at the $3.7 billion Patelco Credit Union in Pleasanton, Calif.

Vitale said receiving a second payment usually goes smoothly. The friction is with the first-time recipient who does not need to be a member of Patelco but does need to be enrolled in a P2P network. Dwolla is one such, Fiserv's Popmoney is another and there are many more.

So far, penetration is low, experts say. Mike Salerno, e-services manager at the $5.2 billion America First Credit Union in Ogden, Utah, said the financial institution is sending out a few hundred P2P transfers each month.

It's a similar story at Patelco, where around 6% of online users also use P2P, Vitale said. At Financial Plus, Cale said about 1% of the credit union's home banking users are using P2P.

"We have done no advertising for it. Those who use it have discovered it themselves," Cale pointed out.

Tiny adoption is not the only puzzlement around P2P. Another perplexity is that, going into this, most experts believed the tools would be used for casual payments in typically small amounts: chipping in $10 towards a shared lunch tab, for instance, or maybe $25 towards a retirement gift for a co-worker. However, that is not how P2P has shaped up.

Tom Roberts, a senior vice president of Fiserv's CashEdge, said that payments are proving to be in higher amounts: a roommate's share of rent or parents sending money to a child at college. Rather than low, two-figure amounts, some transactions are going into the three-figure category, he noticed. Vitale said Patelco's average P2P is around $650.

As for who is using it, Roberts said it is a bimodal distribution. The biggest group is the 22- to 32-year old age group followed by those ages 46 to 56, who, Roberts suspects is frequently sending money to their children in their 20s.

Still, P2P may have one major barrier, Milne said.

"P2P will always be a limited market.  It is not where people spend most of their money."

Mortgage and car payments, insurance bills, utilities, grocery store and credit cards – those are where the big dollars change hands and all of them are well-handled by more traditional payments tools, some experts agree. P2P is unlikely to make inroads into those niches, leaving it with a comparatively small field of use.

Either way, are there enough users to produce a fire under P2P in 2012?  Some experts continue to be bullish. Roberts expects much broader adoption as more institutions tightly integrate P2P into both online banking and mobile apps.