Just because I like Rube Goldbergs…
OK, cell A1 has your dates, like “1/1/08 & 1/3/08 & 1/5/08”
In B1, you put the formula:
=MID(A1,1,SEARCH("&",A1,1)-1)
In C1, you put the formula:
=MID(A1,LEN(B1)+2,SEARCH("&",A1,LEN(B1)))
In D1, you put the formula:
=MID(A1,LEN(B1)+LEN(C1)+4,SEARCH("&",A1,LEN(B1)+LEN(C1) + 1))**
…and so on for a sufficient number of columns to cover the maximum number of dates you might have in A1. Note that the number after the LEN() statement and the number at the very end of the formula (in italics) increase by 2 and 1, respectively, every additional column. You can put these colums out of the way or hide them if you don’t want them to show up to users. This splits your dates into a varying number of multiple columns.
In E1 (or wherever you want the finished data to go, you put:
=TEXT(TRIM(B1),“dddd”)& " & " & TEXT(TRIM(C1),“dddd”)& " & " & TEXT(TRIM(C1),“dddd”)
You will probably want to put some “IF” logic in there so you won’t get “& &” with no dates between them.
Then, and this is the most important step, give yourself 50 lashes for having non-discrete data in spreadsheet cells 
Best of luck!