Is it generally acceptable to ask another lab for cell line/plasmid/etc - (Feb/09/2014 )

Let's say a lab that works on something completely irrelevant to what you work on but they've designed a plasmid or a cell line that you could really use.  Is it acceptable to ask them whether they may share it with you?  If so, what arrangement is usually made (e.g. name on paper)?

Yes, it is acceptable usually, and is considered to be good practice for the open scientific community/collaboration.  However, some labs are either too busy to respond or don't want to respond so you may not get a reply.   If it is a commercial company that has the line - you can usually pay them for it.   Sometimes the plasmid or cell line is deposited with a repository such as Addgene or ATCC, in which case you can get it from there.

In these days of translational science you will probably have to sign a Material Transfer Agreement, which the lawyers for the respective institutions will have to work out.  Names on papers aren't frequently required, but it depends on the person/lab and the agreement signed, often acknowledgement of the contribution and an appropriate citation of their paper is all that is required for plasmids.  I don't know about cell lines as a lot more work goes into those.

You will most likely have to pay shipping costs for cell lines, but most labs are happy to spot some plasmid on filter paper and mail it to you.

There are also specialised deposit authorities such as DSMZ or NCPPB (and several others) where you can order e.g. cell lines which they have in their culture collections. But here you have to pay usually, but you can be at least very sure that they know what they culture.

How can you tell if an author deposited their plasmid or cell line in a repository?  Would it say on the manuscript?

Sometimes it is mentioned in the paper, but not always as these things are often done after the papers are published - the best bet is to contact the authors if possible, and they will refer you to the repository if necessary.