The song book that we use at our church is rather pieced together, and I am looking for software that I can use to scan it all in, and set all the songs to the same font. The only thing I know of is Photoscore, but that is a little out of my budget. If you know of anything open source for Linux, that would be great.

OCR is not one of the strong points on Linux. Though admittedly I haven't checked in a couple of years so maybe it has improved a bit.

Scanning the images shouldn't be difficult if you have a device that's compatible with SANE (the scanning foundations for Linux). However translating the images into scores is the OCR task, and that's another matter.

If you know about some windows program that can do it, you can always try to run it under wine as last resort.

If you can't find a program that can acceptably convert all the scores (or at least an acceptable number of them), then you are going to have to do a lot of manual work and rewrite the scores. There are lots of programs that can do that.

Not aware of anything for scanning the music into an editable format for Linux..
but you can look at these Score projects, maybe one will address your needs.

Lilypnd
noteedit
Rosegarden
Denemo
musescore
abc

http://linux-sound.org/notation.html

http://www.linux.com/feature/118302
http://musescore.org/
http://www.linuxjournal.com/article/8629