Update: Version 1.2 is available to download, adding support for custom Twitter API keys. This was requested by some users to increase reliability. Version 1.0 and 1.1 do not work any more due to changes in Twitter's API.
Searchtweet is a mxj external that searches twitter with a given keyword and returns a desired maximum number of most recent posts, with username, date and twitter text body routed to separate outlets. The object returns a specified number of most recent twitter posts that contain a given keyword, #hashtag, or @usertag.
Advanced search queries also work:
Unless custom API keys are entered, the plugin will default to its own authentication keyset. This may limit the number of searches per given time. Eg. You must optimize your search frequency to avoid hitting the API rate-limits. (Ex. Do not connect a [metro 10] to the inlet, your IP will be banned in no second)
For more info: