Lion has several sources for scanner support.  This Apple article lists scanners and printers that they have:

http://support.apple.com/kb/HT3669

To update the support for those scanners, they have links for driver updates from these vendors HP, Ricoh, Canon,Epson,Brother,Lexmark, Samsung, Fuji/Xerox which if updated after July 20, 2011 for Lion

These other sources have scanners:

Open source support from: http://www.ellert.se/twain-sane/ together with http://www.sane-project.org/sane-mfgs.html

Exactscan has several compatible: http://www.exactscan.com/download/compatiblescanner.html

Some HP ones have a trick you can do as documented by this thread:

http://discussions.apple.com/thread.jspa?messageID=5786673#5786673

http://www.hamrick.com/ Vuescan has support for these scanners: http://www.hamrick.com/vuescan/supported-scanners.html

Image Capture support http://macmanus.nl/2013/11/28/use-unsupported-scanner-in-mavericks/ (also lists Lion)

http://www.silverfast.com/show/lion-2/en.html has  Lion support for numerous scanners.