Maybe if you have no savings at all, and a small checking account.
I personally keep enough in my checking to cover "float" each month (mortgage + bills + maybe $2000 amount of spending money). Then there is 6 to 12 months worth of expenses in a ING-Direct-type high interest savings. Then the Roth IRA gets maxed out, Then the 401K gets maxed to the point that my employer stops matching. The rest gets invested in the market (mostly in ETF's / ETN's purchased in my brokerage account).