You can create your own version of a ST bond fund, like
Vanguard's ST investment grade (VFSTX) with CD's if you so choose since the ST bond fund is just a ladder of 0-5 year bonds [granted with about 800 bonds to manage credit risk]. For example, if you averaged current offerings of 1,2,3,4 + 5 year CDs, you'd likely get an average yield of about 4.65% or so, which is roughly what VFSTX is yielding. But you wouldn't be taking any credit risk.
VFSTX has done the worst of the ST bond funds simply b/c there's been a flight to quality, meaning that everybody's been fleeing towards treasury and US agency bonds. Note the very good relative performance of all of Vanguard's treasury/TIPS funds vs. similar maturity bond funds with corporate bonds.
- Alec