I don't fully understand your goal, and I don't know delicious... but I
give you my best guess on the issue.
Suppose there are only one input field for users to input for tags,just
as delicious do, how to let each tag include space? eg:
The user inputed as follows:
ruby on rails ajax web development
And the user want "ruby on rails","ajax","web development" to be
tagged,if he inputs as:
ruby on rails,ajax,web development
Then it can be resolved,however,it seems that it does not fit for one's
inputing habbit,does there exist better way?
Well, it all depends on how "psiquic" you want your software to be.....
You could match your input with some regular expressions, and try to
"guess" what the user wanted to enter.... but it would be no better
than that: a guess. Maybe "agents" could help, but then again: these
would just be more advanced guesses!
If you want the client to "control" wich tags will be entering, you
need a "tag" separator. say: | , ; : or whatever.
Hope this helps,