Revision 9ec24dc2-a57c-4f39-b75b-0930ca8a25b9 - Code Golf Stack Exchange

###GolfScript, 39 characters###

 :I{97,26,{97+}%{[.32-]I\-,}$+'{|}~'+=}%

[Online version](http://golfscript.apphb.com/?c=OyJMb3JlbSBpcHN1bSBkb2xvciBzaXQgYW1ldCwgY29uc2VjdGV0dXIgYWRpcGlzY2luZyBlbGl0LiIKCjpJezk3LDI2LHs5Nyt9JXtbLjMyLV1JXC0sfSQrJ3t8fX4nKz19JQ%3D%3D&run=true) for testing. Note that the sorting is not defined if multiple characters have the same count in the input string.

*Example output*

> Lvgld rqfjd uvmvg frh edlh, svpflshlhjg eurqrfsrpn lmrh. Njps flu ujr
> eh prfr ljrfdvu qlmmlphlfbjl es flu lprd. Njmmed ejshvg ojfhv bjrf
> ured tejsrijf, lj tgrpnrmme lfh qvghhrhvg. Plmmlphlfbjl wlm qaeglhge
> prfm. Vlfhrijmjd svpnjl jmhgrslf denpe e tgrpnrmme. Qjrfbjl qvghhrhvg,
> grfjf fjfsrqrh qlmmlphlfbjl hgrfhrbjl, vgsr mvgld essjdfep prfr,
> fslmlgrfbjl wrwlgge hjgqrf dlhjf frh edlh feqrlp. Fjfsl tesrmrfrf ured
> hjgqrf, pls mvivghrf ujr imepurh pls. Vlfhrijmjd es jgpe jh mesjf
> svddvuv fvmmrsrhjurp pls pvp wlmrh. Njmme sjgfjf jgpe fld, eh
> hrpsrujph fld dvmlfhrl wlm. Njmmed tgrpnrmme ephl lj uvmvg irilpujd,
> qvfjlgl resjmrf pjps mesrpre. Slu es qglhrjd lfh, wlm fslmlgrfbjl
> prfm. Paeflmmjf mvivghrf uvmvg fvuemlf feqrlp dvmmrf alpuglgrh.
> Iphlnlg fslmlgrfbjl hldqvg hlmmjf, wrwlgge wegrjf plbjl dehhrf rp.
> Iphlnlg qvghe wlfhrijmjd prfm, lh tljnreh hvghvg hrpsrujph wlm. Alplep
> urnprffrd lmlrtlpu tejsrijf. Mvgir pls plbjl wlm ephl qjmwrpeg dvmmrf
> lj rp rqfjd.