The find:

• -name '*.log' -- match files ending with .log
• -mtime -2 -- match files modified within the last 2 days
• -exec CMD ARGS \; -- for each file found, execute command, where {} in ARGS will be replaced with the file's path

The grep:

• -c is to print the count of the matches instead of the matches themselves
• -H is to print the name of the file, as grep normally won't print it when there is only one filename argument
• The output lines will be in the format path:count. Files that didn't match "Exception" will still be printed, with 0 as count
• The second grep filters the output of the first, excluding lines that end with :0 (= the files that didn't contain matches)

Extra tips:

• Change "Exception" to the typical relevant failure indicator of your application
• Add -i for grep to make the search case insensitive
• To make the find match strictly only files, add -type f
• Schedule this as a periodic job, and pipe the output to a mailer, for example | mailx -s 'error counts' yourmail@example.com

The -H flag of grep may not work in older operating systems, for example older Solaris. In that case use ggrep (GNU grep) instead, if it exists.