No one thought it could happen. Those who followed Wall Street closely knew, of course, that Treasury Secretary Henry Paulson and Lehman Brothers CEO Dick Fuld had essentially been playing chicken with the bank's future--or so it seemed. But when neither Bank of America nor Barclays purchased the firm, on September 15, 2008, Lehman was forced into what became the largest U.S. Chapter 11 bankruptcy ever, and the Treasury secretary refused to make a loan to keep the bank afloat.

That set off the 2008 financial crisis in earnest, leading to the Great Recession.

Few entrepreneurs, of course, had accounts with Lehman or an investment-banking relationship with the firm. But its collapse still had startling implications for them, affecting everything from their ability to access credit to their luck at hiring software developers.

Four years later, here's how the entrepreneurial landscape has changed--all thanks to a big firm that no longer exists.

Financing has never been cheaper--or more difficult to obtain.

On the face of it, small-business loans should be a bargain: The Federal Reserve funds rate won't rise to much more than zero until at least 2014. Plus, interest-rate spreads are narrowing as bank competition heats up.

The tough part is getting approved for one of those (seemingly) cheap loans. Small-business lending standards have barely eased since ratcheting up in 2008, according to the Fed's monthly loan officer surveys. The result: Just 30% of small businesses are borrowing, according to the latest report from the National Federation of Independent Business. That's just one point above the country's record low. Meanwhile, the Dodd-Frank Act has put in place new capital requirements, meaning banks will likely require even bigger down payments, more collateral, and more stringent personal guarantees. So while the interest rates may be cheap, that loan could cost you in other ways.

Pessimism permeates the small-business community.

Economists tell us the Great Recession ended in June 2009. But three years of a recovery that hardly deserves the name have really taken their toll.

In 2009, the number of business owners who said they expected the economy to improve in the next year was 11% higher than the number who said they thought it would decline, according to the National Federation of Independent Business. In contrast: The NFIB's most recent poll showed that those who thought the economy was going to get worse before it got better outweighed the optimists by 2%. 

Figures from the National Small Business Association, another advocacy group, are even less hopeful. In its most recent poll, 40% of its membership said they were not confident in the future of their own business. That's the highest that figure has been in five years.

A pessimistic view of the economy affects both investment and hiring--two factors that have to rebound for the economy to really gather steam. Historically, small businesses have been the ones to lead the country out of recession. This time around, that's not happening. Only 15% of the NSBA's members said they plan to hire someone in the next six months. Instead, it's multinational corporations, expanding overseas, that are driving job growth. 

For engineering talent, Wall Street has lost (some of) its sheen. 

In the years preceding the financial crisis, investment-banking firms scoured the nation's top colleges for the brightest software engineering grads they could find. Algorithmic trading was booming, and Wall Street could offer entry-level engineers starting salaries of around $100,000, says Hong Quan, a former Wall Street trader who now runs Quantum Startups, a Silicon Valley recruiting firm. Start-ups competing for the same talent could offer equity, but they couldn't come close to matching salaries. 

Fast-forward to today's post-financial meltdown ecosystem. Wall Street salaries still lure some top grads, but many engineers in particular are looking at their job prospects differently. Start-ups no longer seem like such a risky bet after watching financial firms purge thousands of employees.

"Some Wall Street engineers need no persuasion, for the simple reason that their firms are smaller or gone," says Bruce Gibney, a partner at the San Francisco-based VC firm Founders Fund. "The most common answer I've heard to 'Why not Goldman Sachs?' is that engineers believe that Silicon Valley offers both better economic expectations now and, more importantly, the opportunity to work on projects that are significantly more positive sum than finance seems to be overall."

That doesn't necessarily mean that it's easier to snag top engineering talent anywhere, though. Tech start-ups have become hot--and that's exactly the problem.

"Engineers want to work for smart people solving hard problems in an environment they enjoy," says Michael Morell, founder of Riviera Partners, a recruiting firm that has found new hires for the likes of Twitter, LinkedIn, Groupon, and Pinterest. And now there are a lot of start-ups that can offer exactly that. Thus, Morell says, "the talent pool is spread thin across too many companies."