Twitter’s hiring continues apace. The hot, well-funded microblogging startup was up to 175 employees at its inaugural developer conference Chirp. And now it has snatched one more key hire for its vice president of engineering slot: former Palm senior vice president Michael Abbott.

SEC filings Friday revealed the executive, who was critical to the development of its Web OS platform, had recently left the mobile device company.

As he moves in, current vice president of engineering Greg Pass moves up to the chief technology officer role. He was a cofounder of Summize, the early real-time search engine the microblogging company bought in 2008. Twitter now claims that it performs more searches than Yahoo or Microsoft’s Bing.