Assuming there is one ID per line in a file named "ids.txt", do this from a bash shell:

while read id; do wget http://www.uniprot.org/uniprot/$id.txt; done < ids.txt

For a non-programatic way of addressing the question...

If you go to the "Retrieve" tab at the top of the UniProt webpage http://www.uniprot.org/ , you can upload a file with a list of IDs in it, or just copy-and-paste into the query box. You can then get them in GFF, "Flat Text", FASTA, XML formats. This help page on the UniProt site gives more information about this http://www.uniprot.org/help/batch

If you want few files sequences do it manually via http://www.uniprot.org/uniprot/SWISSPROT_ID_YOU_WANT.txt
changing ID every time.
or If you are using windows "wget" is the best tool for downloads via command prompt.

This could help http://biopython.org/DIST/docs/tutorial/Tutorial.html#htoc132