In a somewhat surprising announcement, SirsiDynix announced late last week that it had a “new investment partner,” Vista Equity. Details were scant but a formal (and only slightly more detailed) press release (pdf) was issued yesterday. Vista is a private equity firm with over $1 billion in capital, primarily in the software and technology sectors. SirsiDynix, of course, is one of the biggest players in the market, with nearly 4,000 clients. Sirsi and Dynix merged only 18 months ago to create the largest company in the library automation sector. “We are long-term investors in technology companies that are committed to …