If you rollover to an IRA, then you will not be able to use the money for a loan as Martha noted above.
If you can transfer it into your new employer's 401(k), then --- if you employer has loan provisions -- you might be able to use it for a loan in an extended emergency.
I had a colleague who had a short sale on his old house. He needed cash to cover the short sale. He had rolled over his old 401(k) to an IRA. So he had to cash in the IRA, pay the 10% penalty, pay the income taxes and generally get screwed on the whole deal. If he had rolled his old 401(k) in to his new 401(k), he would've been able to get a loan from the 401(k), cover the short sale, no penalties and no extra income taxes.
Sure, borrowing from your 401(k) is not a great idea, but when you are between a rock and a hard place, you gotta do what you gotta do. And cashing in an IRA was worse than borrowing from a 401(k).