An Old Irish Blessing, reasked (without using encodings)

Golfscript, 198 characters

[]"-!9 4(% 2/!$<)3A50H/ -%%4 9/5
XXXN7).X\"?!,7I3>4UU2I!#+
[[[S35.;(`A[2- 50/.]]]&]%
YO2!U3F|,`/&4ZZZZZK)%,$3
!.$ }4),ze-%%Z!'!k\n-!9 '/S(/]hh )o4(%GG,/7 /&A)3;!v"{.32>{.58<{32+}{56-~1$>2<}if}*+}/+

Output:

$ ruby golfscript.rb blessing.gs
MAY THE ROAD RISE UP TO MEET YOU
MAY THE WIND BE ALWAYS AT YOUR BACK
MAY THE SUN SHINE WARM UPON YOUR FACE
THE RAINS FALL SOFT UPON YOUR FIELDS
AND UNTIL WE MEET AGAIN
MAY GOD HOLD YOU IN THE HOLLOW OF HIS HAND

The poem is compressed to 158 characters by using part of the ASCII range for back-references (of fixed length 2). The coding scheme is as follows:

[10]      : newline (unencoded)
[32]      : space (unencoded)
[33..57]  : literal (33=A, 34=B, ... 57=Y, Z not needed)
[58..126] : back-reference relative to the end of the decompressed string so far. 

The remaining 40 characters make up the decompression code which can probably be golfed a little further, since this is my first attempt at Golfscript.

---

Case-sensitive version, 207 characters

Same concept, but trading some of the back-reference range for lower case letters at the cost of some compression.

[]"-AY THE ROAD RISaUPhO MEET YOU
xxxnWINxB_ALWiS^TuuRiACK
{{{sSUN[HINa{RM UPON}}}F}E
4HoRAuS fLL SOFTzzzzzkIELDS
!NDlNTIwWE MEEzAGAIN
-AY 'OsHOLxYOU k THEggLOW OF (ISeAND"{.32>{.90<{32+}{88-~1$>2<}if}*+}/+

Output:

$ ruby golfscript.rb blessing-casesensitive.gs
May the road rise up to meet you
May the wind be always at your back
May the sun shine warm upon your face
The rains fall soft upon your fields
And until we meet again
May God hold you in the hollow of His hand

Perl, 214 characters

s//01road rise2 to 34
01w5d be always at4r back
01s7 sh5e warm284r face
The ra5s fall soft284r fields
And 7til we 3 aga5
0God 6d4 5 1 6low of His hand/;s/\d/('May ','the ',' up',meet,' you',in,hol,un,on)[$&]/eg;say