Sub Button1Click(sender As Object, e As EventArgs)
  Dim Username, Passwort, UpdateTXT As String
  'identi.ca-Userdaten...		
  Username = "testuser"
  Passwort = "123456789"
  ' String aus dem TExtfeld lesen....
  UpdateTXT = txtDent.Text
  'aufrufen von curl.exe
  Shell("curl -u " + Username + ":" + Passwort + " -d status=" + Chr(34) + _
    UpdateTXT + Chr(34) +  " http://identi.ca/api/statuses/update.xml")
 
End Sub

Function Str2UTF8(Text As String) As String
	Text = Replace(Text, "à", "Ã ")
	Text = Replace(Text, "Ä", "Ä")
	Text = Replace(Text, "ä", "ä")
	Text = Replace(Text, "Ç", "Ç")
	Text = Replace(Text, "ç", "ç")
	Text = Replace(Text, "É", "É")
	Text = Replace(Text, "é", "é")
	Text = Replace(Text, "ê", "ê")
	Text = Replace(Text, "È", "È")
	Text = Replace(Text, "è", "è")
	Text = Replace(Text, "Ø", "Ø")
	Text = Replace(Text, "ø", "ø")
	Text = Replace(Text, "ö", "ö")
	Text = Replace(Text, "Ö", "Ö")
	Text = Replace(Text, "ß", "ß")
	Text = Replace(Text, "Ü", "Ãœ")
	Text = Replace(Text, "ü", "ü")
	Text = Replace(Text, "ý", "ý")
	Str2UTF8 = Text
End Function

Public Shared Sub PostDent(username As String, password As String, dent As _
  String)
	Try
		Dim user As String = Convert.ToBase64String( _
  System.Text.Encoding.UTF8.GetBytes(username & ":" & password))
		Dim bytes As Byte() = System.Text.Encoding.UTF8.GetBytes("status=" & dent)
		Dim request As HttpWebRequest = DirectCast(WebRequest.Create( _
  "http://identi.ca/api/statuses/update.xml"), HttpWebRequest)
		request.Method = "POST"
		request.ServicePoint.Expect100Continue = False
		request.Headers.Add("Authorization", "Basic " & user)
		request.ContentType = "application/x-www-form-urlencoded"
		request.ContentLength = bytes.Length
		Dim reqStream As Stream = request.GetRequestStream()
		reqStream.Write(bytes, 0, bytes.Length)
		reqStream.Close()
		Catch ex As Exception
	End Try
End Sub

Dim bytes As Byte() = System.Text.Encoding.UTF8.GetBytes("status=" & dent)

Dim bytes As Byte() = System.Text.Encoding.ASCII.GetBytes("status=" & _
  System.Web.HttpUtility.UrlEncode(dent, System.Text.Encoding.UTF8))