They won't work on a Sony alpha as they only accept minolta AF. I found this out the hard way. however you may be able to find an adapter. I got a reversing ring for my minolta MD and am attemping to use it as a macro style lens. Either way I think you would loss the auto focus. Check out http://www.srb-griturn.com/index.asp they have loads od adapters and such!
You CAN use them on Sony/Minolta AF cameras's, you just need an adaptor. SRB Griturn sell one for £42.
You can also get adaptors to Canon and Nikon from Roxsen. They are about £20, come from the states and you'd have to buy through eBay. Minolta MD to Nikon is here and Minolta MD to Canon EOS is here
Whether it's worth spending the money on the adaptor really depends on what lenses they are though. Also remember that because the adaptors add extra length (albeit a small amount) you can find that your focus is off. It's common with Canon to Nikon (and vice versa) convertors that infinity focus is actually slightly off once you use the adaptor. The Roxsen Minolta to Canon convertor says it's got true infinity and I don't know if it's a problem with Nikon.